GBCI Glacier Bancorp Inc

As filed with the Securities and Exchange Commission on February 27, 2025

Registration No. 333-   

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-4

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

GLACIER BANCORP, INC.

(Exact name of registrant as specified in its charter)

49 Commons Loop, Kalispell, Montana 59901 (406) 756-4200

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

RANDALL M. CHESLER

President and Chief Executive Officer

49 Commons Loop

Kalispell, Montana 59901

(406) 756-4200

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies of communications to:

Approximate date of commencement of proposed sale of securities to the public:

As soon as practicable after this Registration Statement becomes effective and upon completion of the merger described in the enclosed document.

If the securities being registered on this Form are being offered in connection with the formation of a holding company and there is compliance with General Instruction G, check the following box. ☐

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided purchase to Section 7(a)(2)(B) of the Securities Act. ☐

If applicable, place an X in the box to designate the appropriate rule provision relied upon in conducting this transaction:

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, as amended, or until the Registration Statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

350 Memorial Drive, Suite 200, Idaho Falls, Idaho 83402

NOTICE OF SPECIAL MEETING OF SHAREHOLDERS OF

BANK OF IDAHO HOLDING CO.

TO BE HELD ON [ ], 2025

To the Shareholders of Bank of Idaho Holding Co.:

A special meeting of the shareholders of Bank of Idaho Holding Co. (“BOID”) will be held on [  ], 2025 at [    ] Mountain Time, at One Capital Center, 999 W Main St., Boise, Idaho 83702 in the 14^th floor conference room. The special meeting is for the following purposes:

Holders of record of BOID common shares at the close of business on [  ], 2025, the record date for the special meeting, are entitled to notice of and to vote at the special meeting or any adjournments or postponements of it. Holders of BOID non-voting Class B shares are entitled to notice of the special meeting but are not entitled to vote at the special meeting. The affirmative vote of the holders of at least a majority of the outstanding shares of BOID’s common stock entitled to vote is required for approval of the merger agreement. To that end, BOID’s directors, executive officers and certain significant shareholders have signed agreements to vote their shares in favor of approval of the merger agreement. As of the record date, to BOID’s knowledge, such persons were entitled to vote 1,603,411 shares representing approximately [   ]% of all outstanding BOID common shares entitled to vote at the special meeting. As of the record date, there were [   ] BOID common shares outstanding and [   ] Class B non-voting common shares outstanding.

Your vote is important. Whether or not you plan to attend the special meeting, we encourage you to submit a proxy to vote your shares as promptly as possible in order to make certain that you are represented at the meeting. You may submit a proxy over the Internet, as well as by telephone or by completing, signing, dating and promptly returning the accompanying proxy using the enclosed envelope. If for any reason you should desire to revoke your proxy, you may do so at any time before it is voted at the meeting. If you do not vote your shares, it will have the same effect as voting against the merger.

The board of directors of BOID has determined that the merger agreement is fair to, advisable, and in the best interests of BOID and its shareholders and unanimously recommends that you vote FOR approval of the merger agreement, FOR approval of the amendment to BOID’s Articles of Incorporation, and FOR approval of the adjournment proposal. With regard to its recommendation that shareholders vote FOR approval of the merger agreement, the board of directors of BOID considered a number of factors, as discussed in “Background of and Reasons for the Merger” beginning on page 27. Such factors also constituted the reasons that the board of directors determined to approve the merger agreement.

Important Notice Regarding the Availability of Proxy Materials for the

Special Shareholders’ Meeting to be held [   ] 2025:

The proxy statement and notice of special meeting are available at [   ]

REFERENCES TO ADDITIONAL INFORMATION

Glacier

This proxy statement/prospectus incorporates important business and financial information about Glacier from documents that Glacier has previously filed with the Securities and Exchange Commission (“SEC”) and that are contained in or incorporated by reference into this proxy statement/prospectus. For a listing of Glacier documents incorporated by reference into this proxy statement/prospectus, please see the section entitled “Where You Can Find More Information.” This information is available for you to review at the SEC’s website at http://www.sec.gov.

You may request copies of this proxy statement/prospectus and any of the documents incorporated by reference into this proxy statement/prospectus or other information concerning Glacier, without charge, by telephone or written request directed to:

Glacier Bancorp, Inc.

49 Commons Loop

Kalispell, Montana 59901

ATTN: Ron Copher, Corporate Secretary

Telephone: (406) 751-7706

Reports that Glacier files with the SEC and certain other documents can also be found on Glacier’s website at www.glacierbancorp.com.

Glacier’s common stock is traded on The New York Stock Exchange under the symbol “GBCI.”

You will not be charged for the documents that you request. If you would like to request documents, please do so by [    ], 2025, in order to receive them before the BOID special shareholders’ meeting.

Bank of Idaho Holding Co.

BOID does not have a class of securities registered under Section 12 of the Securities Exchange Act of 1934 (the “Exchange Act”), is not subject to the reporting requirements of Section 13(a) or 15(d) of the Exchange Act, and accordingly does not file documents or reports with the SEC.

If you have questions concerning the merger or this proxy statement/prospectus or need help voting your shares, would like copies of this proxy statement/prospectus, or would like copies of BOID’s historical consolidated financial statements, articles of incorporation or bylaws, please contact:

Bank of Idaho Holding Co.

350 Memorial Drive

Suite 200

Idaho Falls, Idaho 83402

ATTN: Shanon Taylor, Corporate Secretary

(208) 528-3008

TABLE OF CONTENTS

Appendix A – Plan and Agreement of Merger, dated as of January 13, 2025

Appendix B – Sections 30-29-1301 through 30-29-1340 of the Idaho Statutes, Regarding Appraisal Rights

Appendix C – Opinion of MJC Partners, LLC, Financial Advisor to Bank of Idaho Holding Co.

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QUESTIONS AND ANSWERS

Why am I receiving these materials?

Bank of Idaho Holding Co. (“BOID”) is holding a special meeting of its shareholders to vote on proposals relating to its proposed merger with Glacier Bancorp, Inc. (“Glacier”). We are sending you these materials to solicit your proxy to vote in favor of approval of the merger and to help you decide how to vote your shares of BOID common stock on all matters being considered. The merger cannot be completed unless BOID receives the affirmative vote of the holders of at least a majority of the outstanding shares of BOID’s common stock entitled to vote on the matter. Holders of BOID common shares as of the record date are entitled to vote at the special meeting; however, holders of BOID non-voting Class B shares are not entitled to vote. Information about the special meeting is contained in this document. See “BOID Special Shareholders’ Meeting.”

This document is both a proxy statement of BOID and a prospectus of Glacier. It is a proxy statement because the officers and board of directors of BOID (the “BOID Board”) are soliciting proxies from BOID’s shareholders in connection with voting on the merger and approval of the amendment to BOID’s Articles of Incorporation. It is a prospectus because Glacier will issue, and you will acquire in exchange for your BOID common stock, shares of Glacier’s common stock in exchange for BOID common shares as the consideration to be paid in the merger.

What will happen in the merger?

In the proposed merger, BOID will merge with and into Glacier, with Glacier surviving the merger. Immediately following the merger, Bank of Idaho (the “Bank”) will be merged into Glacier’s subsidiary Glacier Bank. Shares of Glacier will continue to trade on The New York Stock Exchange, with the trading symbol “GBCI.”

What will BOID shareholders receive in the merger?

Under the terms of the merger agreement, all outstanding BOID shares (including each outstanding share of restricted stock and share to be issued upon settlement of restricted stock units (“RSU”) and each outstanding BOID non-voting Class B share) will be exchanged for 1.1000 shares of Glacier common stock (the “per share stock consideration”), subject to certain adjustments as set forth in the merger agreement, with cash paid in lieu of fractional shares.

Assuming for purposes of illustration only that the average closing price for Glacier common stock is $ [   ] (which was the closing price of Glacier common stock on [   ], 2025) and no adjustments are made to the per share stock consideration, each BOID common share and each BOID non-voting Class B share would be exchanged for 1.1000 shares of Glacier common stock with a value equal to $[   ].

Under what circumstances can the merger consideration be adjusted?

Under the terms of the merger agreement, there are certain limited circumstances in which the merger consideration may be adjusted. The per share stock consideration will be subject to reduction if the “BOID Closing Capital,” as defined and determined in accordance with the merger agreement, is less than $122,126,000, subject to certain adjustments. In such event, the number of shares of Glacier common stock to be issued will be reduced on a per-share basis in accordance with the formula set forth in the merger agreement. See “The Merger – Merger Consideration” and “ – Calculation of BOID Closing Capital.”

If the BOID Closing Capital exceeds $122,126,000, subject to certain adjustments, BOID may, upon written notice to Glacier and effective prior to the closing of the merger, declare and pay a special dividend to its shareholders in the amount of such excess.

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In addition, if the Glacier average closing price is less than $35.74 and BOID provides notice of an intent to terminate the merger agreement, as described in more detail under “The Merger – Merger Consideration” below, Glacier may elect to increase, on a per-share basis, the number of shares of Glacier common stock to be issued in the merger (or pay additional cash if it so elects). Conversely, if the Glacier average closing price is greater than $53.60 and Glacier provides notice of an intent to terminate the merger agreement, BOID may elect to accept a decrease, on a per-share basis, in the number of shares of Glacier common stock to be issued in the merger. By voting to approve the merger agreement, BOID shareholders will give the BOID Board the authority to elect to cause BOID to accept a decrease, on a per-share basis, in the number of shares of Glacier common stock to be issued in the merger as set forth in the merger agreement and as described in more detail below. See “The Merger – Termination of the Merger Agreement.”

Assuming that all outstanding BOID common shares are exchanged for Glacier common stock as per share stock consideration in accordance with the merger agreement, no additional BOD Options are exercised, and the per share stock consideration is not adjusted as described above, BOID shareholders will receive an estimated [   ] shares of Glacier common stock in the merger, representing approximately [  ]% of Glacier’s outstanding common stock after taking into account Glacier shares to be issued in the merger.

How are outstanding BOID shares of restricted stock, RSUs, stock options, and stock appreciation rights addressed in the merger agreement?

Under the terms of the merger agreement, when the merger agreement becomes effective (the “effective time”), all outstanding shares of restricted stock and RSUs under BOID’s 2019 Equity Incentive Plan (the “Equity Plan”) will automatically vest and RSUs will be settled with BOID common shares, and each resulting BOID common share will have the right to receive the per share stock consideration and cash in lieu of fractional BOID common shares. Outstanding options to purchase BOID common shares (the “BOID Options”) under the Equity Plan and outstanding Stock Appreciation Rights (“SARs”) under BOID’s 2006 Stock Appreciation Rights Plan (together with the Equity Plan, the “BOID Stock Plans”) will be automatically canceled at the effective time, and the holders of BOID Options and BOID SARs will be paid in cash an amount per share equal to the spread, if any, between (a) the product of the average of the closing sales prices of one share of Glacier common stock on The New York Stock Exchange for the 20 trading days ending on the tenth business day immediately preceding the effective date of the merger (the “Glacier average closing price”) multiplied by the per share stock consideration and (b) the exercise price per share of such BOID Option or BOID SAR, net of any cash which must be withheld under applicable tax laws. Any BOID Option or BOID SAR that has an exercise price per share that is equal to or greater than the amount described in (a) above will be cancelled without any payment.

Will I receive any fractional shares of Glacier common stock as part of the merger consideration?

No. Glacier will not issue any fractional shares of Glacier common stock in the merger. Instead, Glacier will pay you the cash value of a fractional share (without interest) in an amount determined by multiplying the fractional share interest to which you would otherwise be entitled by the Glacier average closing price.

How soon after the merger is completed can I expect to receive my merger consideration?

Glacier will work with its exchange agent, Equiniti Trust Company, LLC, to complete the exchange of your BOID stock certificates for consideration payable in the merger as promptly as practicable following the completion of the merger.

Will I be able to trade the shares of Glacier common stock that I receive in the merger?

You may freely trade the shares of Glacier common stock issued in the merger, unless you are an “affiliate” of Glacier as defined by Rule 144 under the Securities Act of 1933, as amended. Affiliates consist of individuals or entities that control, are controlled by or are under common control with Glacier, and include the executive officers and directors of Glacier after the merger and may include significant shareholders of Glacier.

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When will the merger occur?

We presently expect to complete the merger during the second quarter of 2025. The actual timing of the transaction is subject to a number of factors (primarily regulatory approvals), many of which are beyond the control of Glacier and BOID. The merger is conditioned upon and will occur after the approval of the merger agreement by the affirmative vote of holders of at least a majority of the outstanding BOID common shares entitled to vote on the matter at the BOID special meeting, after the merger has received all required regulatory approvals, and following the satisfaction or waiver of the other conditions to the merger described in the merger agreement and summarized under “The Merger” below.

The merger agreement provides that the merger will be completed effective as of the last day of the month occurring at least five business days after the fulfillment or waiver of each condition to the merger and receipt of all required approvals; provided that Glacier will not be required to consummate the merger on May 31, 2025 and any closing that would occur on the last day of a fiscal quarter will occur on the first day of the following month.

If the merger does not occur by October 31, 2025, either Glacier or BOID may unilaterally terminate the merger agreement; provided, however, if as of October 31, 2025, all required regulatory approvals have not been obtained, then the deadline for consummation of the merger will be extended to on or before January 31, 2026, if either Glacier or BOID notifies the other party in writing on or prior October 31, 2025, of its election to extend such date.

Why are BOID shareholders being asked to approve an amendment to BOID’s Articles of Incorporation?

In order to facilitate the merger and induce Glacier to enter into the merger agreement, the BOID Board agreed to approve, and to submit to BOID’s shareholders for approval, an amendment to BOID’s Articles of Incorporation to increase the maximum size of BOID’s board of directors from nine to eleven in order to make the Articles of Incorporation consistent with BOID’s bylaws. The BOID Board has approved this amendment and, through this proxy statement/prospectus, is submitting it to BOID shareholders for their approval.

When and where will the special meeting take place?

BOID will hold a special meeting of its shareholders on [   ], 2025, at [   ] Mountain Time at One Capital Center, 999 W Main St., Boise, Idaho 83702 in the 14^th floor conference room.

Who may vote at the special meeting?

The BOID Board has set [   ], 2025 as the record date for the special meeting. If you were the owner of BOID common shares at the close of business on [   ], 2025, you may vote at the special meeting. Each holder of BOID common shares is entitled to one vote for each BOID common share owned as of the record date. Holders of BOID non-voting Class B shares are not entitled to vote at the special meeting.

What constitutes a quorum for the special meeting?

The quorum requirement for the special meeting is the presence in person or by proxy of a majority of the total number of outstanding BOID common shares entitled to vote.

What vote is required to approve the merger agreement?

Approval of the merger agreement requires the affirmative vote of the holders of at least a majority of the outstanding shares of BOID’s common stock entitled to vote on the matter. As described in this proxy statement/prospectus, BOID’s directors, executive officers and certain significant shareholders have agreed to vote the BOID common shares they are entitled to vote in favor of approval of the merger agreement. As of the record

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date, to BOID’s knowledge, such persons were entitled to vote 1,603,411 BOID common shares, representing approximately [   ]% of all outstanding BOID common shares entitled to vote at the special meeting. See “BOID Special Shareholders’ Meeting” and “The Merger – Voting Agreements.”

What vote is required to approve the amendment to the Articles of Incorporation?

Approval of the amendment to BOID’s Articles of Incorporation requires the affirmative vote of the holders of at least a majority of the outstanding shares of BOID’s common stock entitled to vote on the matter.

What vote is required to approve the adjournment of the special meeting, if necessary or appropriate?

The proposal to adjourn the special meeting, if necessary or appropriate, including adjournments to solicit additional proxies, will be approved if the votes cast in favor of the proposal exceed the votes cast opposing the proposal. BOID’s directors, executive officers and certain significant shareholders have also agreed to vote their shares in favor of any proposal to adjourn the special meeting if there are not sufficient votes to approve the merger agreement. See “The Merger – Voting Agreements.”

Can I vote in person?

Yes. Although the BOID Board requests that you submit a proxy through the Internet, by telephone or by returning the proxy card accompanying this proxy statement/prospectus, all shareholders are invited to attend the shareholders’ meeting. Shareholders of record on [   ], 2025 can vote in person at the special meeting.

How do I vote?

If you were a shareholder of record on [   ], 2025, you may vote on the proposals presented at the special meeting in person or by proxy. We urge you to vote promptly by submitting a proxy to vote through the Internet, by telephone, or by completing the enclosed proxy card. Even if you plan to attend the special meeting, we recommend that you vote your shares in advance as described below so that your vote will be counted if you later decide not to attend the special meeting.

You may cast your vote by submitting a proxy through the Internet or by telephone by following the instructions included on the enclosed proxy card or by mail by completing, signing and dating the enclosed proxy card and returning it to us promptly in the enclosed envelope. Submitting a proxy through the Internet or by telephone or returning the proxy card will not affect your right to attend the special meeting and vote.

If you choose to vote your shares in person at the special meeting, please bring the enclosed proxy card and proof of identification.

If your shares are registered in “street name” in the name of a broker or other nominee and you wish to vote at the special meeting, you will need to obtain a legal proxy from your bank or brokerage firm. Please consult the voting form sent to you by your bank or broker to determine how to obtain a legal proxy in order to vote in person at the meeting.

What if I fail to submit a proxy or to instruct my broker, bank or other nominee?

If you fail to properly submit a proxy or to instruct your broker, bank or other nominee to vote your BOID common shares, and you do not attend the special meeting and vote your shares in person, your shares will not be voted. This will have the same effect as a vote “AGAINST” approval of the merger agreement and “AGAINST” approval of the amendment to BOID’s Articles of Incorporation, but will have no impact on the outcome of the adjournment proposal.

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Can I change my vote after I have submitted my proxy?

Yes. If you do not hold your shares in “street name,” there are three ways you may change your vote at any time after you have submitted your proxy and before your proxy is voted at the special meeting:

If you submit a written notice of revocation, it must be received by BOID’s Secretary prior to the vote at the special meeting. If you grant a new proxy by telephone or Internet, your revised instructions must be received by 11:59 p.m., Mountain Time, one day before the meeting date.

If you have instructed a bank, broker or other nominee to vote your shares, you must follow the directions you receive from your bank, broker or other nominee to change your voting instructions.

What happens if I return my proxy but do not indicate how to vote my shares?

If you sign and return your proxy card but do not provide instructions on how to vote your BOID common shares at the special meeting of shareholders, your BOID common shares will be voted “FOR” the proposal to approve the merger agreement, “FOR” the proposal to amend the Articles of Incorporation, and “FOR” approval of one or more adjournments of the special meeting.

If my shares are held in “street name” by my broker, bank or other nominee, will my broker, bank or other nominee automatically vote my shares for me?

No. Your broker, bank or other nominee will not vote your shares unless you provide instructions to your broker, bank or other nominee on how to vote. You should instruct your broker, bank or other nominee to vote your shares by following the instructions provided by the broker, bank or nominee with this proxy statement/prospectus.

How does the BOID Board recommend that I vote?

The BOID Board unanimously recommends that BOID shareholders vote “FOR” the proposals described in this proxy statement/prospectus, including in favor of approval of the merger agreement and approval of the amendment to the Articles of Incorporation.

What do I need to do now?

We encourage you to read this proxy statement/prospectus and related information in its entirety. Important information is presented in greater detail elsewhere in this document, and documents governing the merger are attached as appendices to this proxy statement/prospectus. In addition, much of the business and financial information about Glacier that may be important to you is incorporated by reference into this document from documents separately filed by Glacier with the SEC. This means that important disclosure obligations to you are satisfied by referring you to one or more documents separately filed with the SEC.

Following review of this proxy statement/prospectus, please submit a proxy through the Internet, by telephone or by completing, signing, and dating the enclosed proxy card and returning it in the enclosed envelope as soon as possible so that your BOID common shares can be voted at BOID’s special meeting of shareholders.

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What happens if I sell my shares after the record date but before the special meeting?

The record date of the special meeting is earlier than the date of the special meeting and the date that the merger is expected to be completed. If you sell or otherwise transfer your shares after the record date, but before the date of the special meeting, you will retain your right to vote at the special meeting, but you will not have the right to receive the merger consideration to be received by shareholders in the merger. In order to receive the merger consideration, a shareholder must hold their shares through completion of the merger.

What do I do if I receive more than one proxy statement/prospectus or set of voting instructions?

If you hold shares directly as a record holder and also in “street name” or otherwise through a nominee, you may receive more than one proxy statement/prospectus and/or set of voting instructions relating to the special meeting. These should each be voted and/or returned separately in order to ensure that all of your shares are voted.

Should I send in my common stock certificates now?

No. Please do not send your BOID common share certificates with your proxy card. You will receive written instructions from Glacier’s exchange agent promptly following the closing of the merger on how to exchange your BOID common share certificates or evidence of uncertificated shares for the merger consideration. In the meantime, you may wish to begin collecting any certificates in your possession.

What risks should I consider in deciding whether to vote for approval of the merger agreement?

You should review carefully our discussion under “Risk Factors.” You should also review the factors considered by the BOID Board in approving the merger agreement. See “Background of and Reasons for the Merger.”

What are the material United States federal income tax consequences of the merger to BOID shareholders?

Glacier and BOID intend for the merger to qualify as a “reorganization” within the meaning of Section 368(a) of the Internal Revenue Code of 1986, as amended (the “Internal Revenue Code”). If the merger qualifies as a reorganization within the meaning of Section 368(a) of the Internal Revenue Code, then for U.S. federal income tax purposes a U.S. holder (as defined below) of BOID common shares or non-voting Class B shares generally will not recognize any gain or loss upon surrendering its shares, except with respect to any cash received or treated as received in the merger and any cash received in lieu of fractional shares. A U.S. holder of BOID common shares or non-voting Class B shares receiving cash in lieu of a fractional share of Glacier common stock will generally recognize gain or loss equal to the difference between the amount of cash received instead of a fractional share and the basis in its fractional share of Glacier common stock. The U.S. federal income tax consequences described above may not apply to all holders of BOID shares. Your tax consequences will depend on your individual situation. Accordingly, we strongly urge you to consult an independent tax advisor for a full understanding of the particular tax consequences of the merger to you. For a detailed discussion of the material U.S. federal income tax consequences of the merger, see “The Merger – Material U.S. Federal Income Tax Consequences of the Merger to BOID Shareholders.”

Do I have appraisal or dissenters’ rights?

Yes. If you are a BOID shareholder (including if you are a holder of BOID non-voting Class B shares) and you do not agree with the merger, do not vote in favor of approval of the merger agreement, and take certain other actions required by Idaho law, you will have appraisal rights under Sections 30-29-1301 through 30-29-1340 of the Idaho Statutes. Exercise of these rights will result in the purchase of your shares of BOID stock at “fair value,” as determined in accordance with Idaho law. If you elect to exercise this right, we encourage you to consult with your financial and legal advisors. Please read the section entitled “The Merger – Appraisal Rights” for additional information.

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Who can help answer my questions?

If you have questions about the merger, the special shareholders’ meeting, or your proxy, or if you need additional copies of this document or a proxy card, you should contact:

Bank of Idaho Holding Co.

350 Memorial Drive

Suite 200

Idaho Falls, Idaho 83402

Attention: Shanon Taylor, Corporate Secretary

Telephone: (208) 528-3008

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RISK FACTORS

In addition to the other information contained in or incorporated by reference into this document, including the matters addressed under the caption “Cautionary Note Regarding Forward-Looking Statements,” you should consider the matters described below carefully in determining whether or not to approve the merger agreement and the transactions contemplated by the merger agreement.

Risks Associated with the Proposed Merger

Because you are receiving a fixed number of shares that may be adjusted and the market price of the Glacier common stock is expected to fluctuate, you cannot be sure of the value of the shares of Glacier common stock that you will receive.

At the time of the BOID special shareholder meeting, and prior to the closing of the merger, you will not be able to determine the value of the Glacier common stock that you will receive upon completion of the merger. Any change in the market price of Glacier common stock prior to completion of the merger will affect the value of the consideration that BOID shareholders will receive in the merger. Common stock price changes may result from a variety of factors, including but not limited to general market and economic conditions, changes in Glacier’s business, operations and prospects, and regulatory considerations. Many of these factors are beyond the control of Glacier or BOID. You should obtain current market prices for Glacier common stock.

The merger agreement provides that the number of shares of Glacier common stock to be issued for each BOID common share and non-voting Class B share in the merger may be decreased or increased, as the case may be, if the average closing price of Glacier common stock, determined pursuant to the merger agreement, is greater than or less than specified prices. If Glacier’s average closing price determined in accordance with the merger agreement is greater than $53.60 and Glacier provides notice of its election to terminate the merger agreement, the BOID Board is expected to determine, without resoliciting the vote of BOID shareholders, whether or not to accept a decrease, on a per-share basis, in the number of shares of Glacier common stock to be issued in the merger to avoid such termination. See “The Merger – Termination of the Merger Agreement.”

The results of operations of Glacier after the merger may be affected by factors different from those currently affecting the results of operations of BOID.

The businesses of Glacier and BOID differ in certain respects, including the markets in which they operate, and, accordingly, the results of operations of the combined company and the market price of the combined company’s common shares may be affected by factors different from those currently affecting the independent results of operations of BOID and Glacier. For a discussion of the business of Glacier and certain factors to be considered in connection with Glacier’s business, see “Information Concerning Glacier” and the documents incorporated by reference in this document and referred to under “Where You Can Find More Information.” For a discussion of the business of BOID and certain factors to be considered in connection with BOID’s business, see “Information Concerning Bank of Idaho Holding Co.” and the documents referred to under “Where You Can Find More Information.”

The merger agreement limits BOID’s ability to pursue other transactions and provides for the payment of a break-up fee if BOID does so.

While the merger agreement is in effect, subject to very narrow exceptions, BOID and its directors, officers, employees, agents and representatives are prohibited from initiating or encouraging inquiries with respect to alternative acquisition proposals. The prohibition limits BOID’s ability to seek offers from other potential acquirors that may be superior from a financial point of view to the proposed transaction. If BOID receives an unsolicited proposal from a third party that is superior from a financial point of view to that made by Glacier and the merger agreement is terminated, BOID will be required to pay a $8,000,000 break-up fee. This fee makes it less likely that a third party will make an alternative acquisition proposal. See “The Merger – Break-Up Fee.”

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Combining the two companies may be more challenging, costly or time-consuming than expected.

Glacier and BOID have operated and, until the completion of the merger, will continue to operate, independently. Although Glacier has successfully completed numerous mergers in the recent past, it is possible that the integration of the Bank into Glacier Bank could result in the loss of key employees, the disruption of the ongoing business of the Bank or inconsistencies in standards, controls, procedures and policies that adversely affect the Bank’s ability to maintain relationships with customers and employees or to achieve the anticipated benefits of the merger. As with any merger of banking institutions, there also may be disruptions that cause the Bank to lose customers or cause customers to take their deposits out of the Bank.

We may face unanticipated costs relating to the merger.

Glacier believes that it has reasonably and conservatively estimated the likely costs of integrating the operations of the Bank into Glacier Bank, and the incremental costs of operating as a combined financial institution. However, it is possible that unexpected transaction costs or future operating expenses, as well as other types of unanticipated costs, including as a result of the substantial commitment of time and resources by Glacier’s management to the merger, could have a negative effect on the results of operations and financial condition of Glacier after the merger.

The merger agreement may be terminated in accordance with its terms and the merger may not be completed, which could have a negative impact on BOID.

The merger agreement is subject to a number of conditions that must be fulfilled in order to close. Those conditions include: approval by the shareholders of BOID, receipt of all required regulatory approvals, the continued accuracy of certain representations and warranties by both parties (subject to the materiality standards set forth in the merger agreement), and the performance by both parties of certain covenants and agreements. In addition, certain circumstances exist in which BOID may terminate the merger, including by accepting a superior proposal. There can be no assurance that the conditions to closing the merger will be fulfilled or that the merger will be completed.

If the merger agreement is terminated, there may be various consequences to BOID, including:

The opinion of BOID’s financial advisor delivered to the BOID Board before the execution of the merger agreement does not reflect any changes in circumstances subsequent to the date of the opinion.

The opinion of MJC Partners regarding the fairness, from a financial point of view, of the per share stock consideration in the merger was delivered to the BOID Board on January 13, 2025, and speaks only as of such date. Changes in operations and prospects of Glacier and BOID, general market and economic conditions, and other factors both within and outside of Glacier’s and BOID’s control may significantly alter the relative value of the companies by the time the merger is completed. MJC Partners’ opinion does not speak as of the time the merger will be completed or as of any date other than the date of such opinion.

After the merger is completed, BOID shareholders will become Glacier shareholders and will have different rights that may be less advantageous than their current rights.

Upon completion of the merger, BOID shareholders will become Glacier shareholders. Differences in BOID’s Articles of Incorporation and BOID’s bylaws and Glacier’s articles and Glacier’s bylaws will result in

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changes to the rights of BOID shareholders who become Glacier shareholders. See “Comparison of Certain Rights of Holders of Glacier and BOID Common Shares.”

BOID’s shareholders will have a significantly reduced ownership and voting interest after the merger and will exercise less influence over management.

BOID’s shareholders currently have the right to vote in the election of the BOID Board and on other significant matters affecting BOID, such as the proposed merger with Glacier. When the merger occurs, each BOID shareholder will become a shareholder of Glacier with a percentage ownership of the combined organization that is much smaller than the shareholder’s percentage ownership of BOID. Based on the anticipated number of Glacier common shares to be issued in the merger, it is anticipated that the BOID shareholders will own approximately [  ]% of all of the outstanding shares of Glacier’s common stock following the merger. Because of this, BOID’s shareholders will have significantly less influence on the management and policies of Glacier than they now have on the management and policies of BOID.

The merger may fail to qualify as a reorganization for federal tax purposes, resulting in the recognition by BOID’s shareholders of taxable gain or loss in respect of their BOID shares.

Glacier and BOID intend the merger to qualify as a reorganization within the meaning of Section 368(a) of the Internal Revenue Code. Glacier and BOID, as a condition to closing, will each obtain an opinion from their respective legal counsel that the merger will qualify as a reorganization for federal tax purposes. These opinions do not bind the Internal Revenue Service or the courts or prevent either from taking a contrary position. Neither Glacier nor BOID has requested and neither intends to request any ruling from the Internal Revenue Service as to the U.S. federal income tax consequences of the merger. Furthermore, if the merger fails to qualify as a reorganization, Glacier, as successor to BOID, may incur a significant tax liability since the merger would be treated as a taxable sale of BOID’s assets for U.S. federal income tax purposes.

Glacier and BOID will be subject to business uncertainties and contractual restrictions while the merger is pending.

Uncertainty about the effect of the merger on employees, customers and vendors may have an adverse influence on the business, financial condition and results of operations of Glacier and BOID. These uncertainties may impair Glacier’s and BOID’s ability to attract, retain and motivate key personnel, maintain current deposit levels, and continue to attract depositors and attract new borrowers pending the consummation of the merger, as such personnel, depositors and borrowers may experience uncertainty about their future relationships following the consummation of the merger. Additionally, these uncertainties could cause customers (including depositors and borrowers), suppliers, vendors and others who deal with Glacier or BOID to seek to change existing business relationships with Glacier, BOID or the combined company or fail to extend an existing relationship with Glacier, BOID or the combined company.

In addition, the merger agreement restricts BOID from taking certain actions without Glacier’s consent while the merger is pending. These restrictions could have a material adverse effect on BOID’s business, financial condition and results of operations. See “The Merger — Covenants” for a description of the restrictive covenants applicable to BOID.

Failure to complete the merger could negatively impact the stock prices and future businesses and financial results of Glacier and BOID.

If the merger is not completed, the ongoing businesses of Glacier and BOID may be adversely affected, and Glacier and BOID will be subject to several risks, including the following:

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In addition, if the merger is not completed, Glacier and/or BOID may experience negative reactions from the financial markets and from their respective customers and employees. Glacier and/or BOID also could be subject to litigation related to any failure to complete the merger or to cause them to perform their respective obligations under the merger agreement. If the merger is not completed, Glacier and BOID cannot assure their respective shareholders that the risks described above will not materialize and negatively affect the business, financial results or stock prices of Glacier and/or BOID.

Shareholder litigation could prevent or delay the completion of the merger or otherwise negatively impact the business and operations of Glacier and BOID.

Shareholders may file lawsuits against Glacier, BOID, and/or the directors and officers of either company in connection with the merger. If any plaintiff were successful in obtaining an injunction prohibiting Glacier or BOID from completing the merger, then such injunction may delay or prevent the effectiveness of the merger and could result in significant costs to Glacier and/or BOID, including any costs associated with the indemnification of directors and officers of each company or the defense or settlement of any shareholder lawsuits filed in connection with the merger. Such litigation could have an adverse effect on the consolidated financial condition and consolidated results of operations of Glacier and BOID and could prevent or delay the completion of the merger.

The merger is subject to the receipt of approvals and/or waivers or non-objections from governmental authorities that may delay the date of completion of the merger or impose conditions that could have an adverse effect on Glacier.

Before the merger may be completed, various approvals, waivers or non-objections must be obtained from state and federal governmental authorities, including the Federal Deposit Insurance Corporation, the Board of Governors of the Federal Reserve System, the Commissioner of the Montana Division of Banking and Financial Institutions, and the Idaho Department of Finance. Obtaining the approval or satisfying the requirements of these governmental authorities may delay the date of completion of the merger, including due to any or all of the following: an adverse development in either party’s regulatory standing or any other factors considered by regulators in granting such approval; governmental, political or community group inquiries, investigations or opposition; or changes in legislation or the political environment. In addition, these governmental authorities may impose conditions on the completion of the merger, or require changes to the terms of the merger. While Glacier and BOID do not currently expect that any such conditions or changes would result in a material adverse effect on Glacier, there can be no assurance that they will not, and such conditions or changes could have the effect of delaying completion of the merger, or imposing additional costs on or limiting the revenues of Glacier following the merger, any of which might have a material adverse effect on Glacier following the merger. The parties are not obligated to complete the merger should any required regulatory approval, waiver or non-objection contain a condition or requirement not normally imposed in such transactions that would deprive Glacier of the economic or business benefits of the merger in a manner that is material relative to the aggregate economic or business benefits of the merger to Glacier.

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Certain BOID directors and executive officers may have interests in the merger that differ from, or are in addition to, the interests of the shareholders.

In addition to their interests as shareholders generally, certain members of the BOID Board and executive management may have other interests in the merger. The BOID Board was aware of these interests and considered them, among other things, when deciding to approve the merger agreement. For a more detailed discussion of these interests, see “Interests of BOID Directors and Executive Officers in the Merger.”

Risks Associated with Glacier’s Business

Glacier is, and will continue to be, subject to the risks described in Glacier’s Annual Report on Form 10-K for the fiscal year ended December 31, 2024, as updated by subsequent Current Reports on Form 8-K, and Quarterly Reports on Form 10-Q, all of which are filed with the SEC and incorporated by reference into this proxy statement/prospectus. See “References to Additional Information” and “Where You Can Find More Information” included elsewhere in this proxy statement/prospectus.

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CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This document, including information included or incorporated by reference in this document, may contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements include, but are not limited to: (i) statements about the benefits of the merger, including future financial and operating results, cost savings, enhancements to revenue and accretion to reported earnings that may be realized from the merger; (ii) statements about Glacier’s and BOID’s plans, objectives, expectations, intentions, projected financial information, future opportunities and any other statements regarding Glacier’s and BOID’s future expectations, beliefs, plans, objectives, results of operations, financial condition and cash flows that are not historical facts; (iii) the expected timetable for completing the merger; (iv) the ability to complete the merger; and (v) other statements identified by words such as “expects,” “will,” “anticipates,” “intends,” “plans,” “believes,” “seeks,” “estimates,” or words of similar meaning. These forward-looking statements are based on current beliefs and expectations of Glacier’s and BOID’s management and are inherently subject to significant business, economic and competitive uncertainties and contingencies, many of which are beyond Glacier’s and BOID’s control. In addition, these forward-looking statements are subject to assumptions with respect to future business strategies and decisions that are subject to change.

In addition to factors previously disclosed in Glacier’s reports filed with the SEC relating to risks to Glacier’s business and stock price, and those identified elsewhere in this document (including the section entitled “Risk Factors”), the following potential factors, among others, could cause actual results to differ materially from the anticipated results or other expectations expressed or implied in the forward-looking statements:

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The foregoing list of factors is not intended to be exhaustive. These forward-looking statements reflect Glacier’s and BOID’s current views with respect to future events and are based on numerous assumptions and assessments made by Glacier and BOID in light of their experiences and perceptions of historical trends, current conditions, business strategies, operating environments, future developments and other factors they believe appropriate. By their nature, forward-looking statements involve known and unknown risks and uncertainties because they relate to events and depend on circumstances that will occur in the future. The factors described in the context of such forward-looking statements in this document could cause Glacier’s and BOID’s plans with respect to the merger, actual results, performance or achievements, industry results and developments to differ materially from those expressed in or implied by such forward-looking statements. Although it is believed that the expectations reflected in such forward-looking statements are reasonable, no assurance can be given that such expectations will prove to have been correct and persons reading this document are therefore cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this proxy statement/prospectus or, in the case of a document incorporated by reference, as of the date of that document. All subsequent written and oral forward-looking statements concerning the proposed transaction or other matters attributable to Glacier or BOID or any person acting on behalf of Glacier or BOID are expressly qualified in their entirety by the cautionary statements above. Neither Glacier nor BOID undertakes any obligation to update any forward-looking statements to reflect circumstances or events that occur after the date the forward-looking statements are made.

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COMPARATIVE STOCK PRICE AND DIVIDEND INFORMATION

Glacier common stock is quoted on The New York Stock Exchange under the symbol “GBCI.” As of the record date, the [   ] outstanding shares of Glacier common stock were held by approximately [   ] holders of record.

On December 19, 2024, Glacier paid a quarterly dividend of $0.33 per share. Glacier has declared 159 consecutive quarterly dividends and has increased the dividend 49 times. Future cash dividends will depend on a variety of factors, including earnings, capital, asset quality, general economic conditions, and regulatory considerations.

The following table presents the trading information for Glacier common stock on January 10, 2025, the last trading day before public announcement of the merger agreement, and [   ], 2025, the latest practicable trading day before the date of this prospectus.

Public trading in BOID’s common stock has not been extensive and such trades cannot be characterized as constituting an active trading market. BOID common stock is not listed on any national securities exchange, although it is quoted on the OTC Markets under the ticker symbol “BOID.” Quotations are based on information received from the OTC Markets based on all transactions reported on the OTC Markets. Such information reflects inter-dealer prices, without retail markups, markdowns or commissions and may not reflect actual transactions. BOID’s common stock is quoted on the OTC Expert Market and quotations in its common stock may be subject to significant fluctuation based on the very limited volume in BOID’s common stock and a single trade may not be indicative of the stock’s long-term trading price. The following table sets forth for the periods indicated, the high and low quotations for BOID common stock along with the aggregate number of shares publicly reported as traded for each applicable quarter.

As of the record date, the [   ] outstanding shares of BOID common stock were held by approximately [   ] holders of record.

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BOID SPECIAL SHAREHOLDERS’ MEETING

Date, Time, Place

The BOID special meeting of shareholders will be held on [   ], 2025, at [   ] Mountain Time at One Capital Center, 999 W Main St., Boise, Idaho 83702 in the 14^th floor conference room.

As described below under “Votes Required and Quorum,” approval of the merger agreement requires the affirmative vote of at least a majority of the outstanding shares of BOID’s common stock entitled to vote on the matter. The proposal to adjourn the special meeting, if necessary or appropriate, including adjournments to solicit additional proxies, will be approved if the votes cast in favor of the proposal exceed the votes cast opposing the proposal.

Purpose

At the special meeting, BOID shareholders will:

Record Date; Shares Outstanding and Entitled to Vote

The BOID Board has fixed the close of business on [   ], 2025, as the record date for determining the holders of BOID common shares entitled to notice of and to vote at the special meeting. Holders of BOID non-voting Class B shares are entitled to notice of the special meeting but are not entitled to vote at the special meeting. At the close of business on the record date, there were approximately [   ] holders of record and [   ] BOID common shares issued and outstanding. Holders of record of BOID common shares on the record date are entitled to one vote per share. Shares of unvested restricted stock and RSUs do not have voting rights.

BOID’s directors, executive officers and certain significant shareholders have agreed to vote all BOID common shares they are entitled to vote that are held or controlled by them in favor of approval of the merger agreement. As of the record date, to BOID’s knowledge, a total of 1,603,411 BOID common shares, representing approximately [   ]% of all outstanding BOID common shares entitled to vote at the special meeting, are subject to voting agreements. See “The Merger – Voting Agreements”.

Votes Required and Quorum

The affirmative vote of the holders of at least a majority of the outstanding shares of BOID’s common stock entitled to vote is required to approve the merger agreement. At least a majority of the total outstanding BOID common shares entitled to vote must be present, either at the meeting or by proxy, in order to constitute a quorum for the special meeting. For purposes of determining a quorum, abstentions and broker non-votes will be counted in determining the shares present at a meeting.

For voting purposes, however, shares must be affirmatively voted FOR approval of the merger agreement in order to be counted as votes in favor of approval of the merger agreement. As a result, abstentions and broker non-votes with respect to the proposal to approve the merger agreement will have the same effect as votes against such proposal.

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The affirmative vote of the holders of at least a majority of the outstanding shares of BOID’s common stock entitled to vote at a meeting in which a quorum is present is required to approve the amendment to BOID’s Articles of Incorporation.

For voting purposes, shares must be affirmatively voted FOR approval of the amendment to BOID’s Articles of Incorporation in order to be counted as votes in favor of the amendment. As a result, abstentions and broker non-votes with respect to the proposal to approve the amendment to BOID’s Articles of Incorporation will have the same effect as votes against such proposal.

The proposal to adjourn the special meeting, if necessary or appropriate, including an adjournment to solicit additional proxies in favor of approval of the merger agreement, will be approved if a quorum is present at the special meeting and the votes cast in favor of the proposal exceed the votes cast opposing the proposal.

Voting, Solicitation, and Revocation of Proxies

If you are a holder of record of BOID common shares as of the record date for the special meeting, there are four ways to have your shares voted:

If the enclosed proxy card is duly executed and received in time for the special meeting, it will be voted in accordance with the instructions given. If the proxy card is duly executed and received but no instructions are given, it is the intention of the persons named in the proxy to vote the shares represented by the proxy FOR the approval of the merger agreement, FOR the approval of the amendment to the Articles of Incorporation, and FOR the proposal to approve one or more adjournments to solicit additional proxies, and in the proxy holder’s discretion on any other matter properly coming before the meeting. Any proxy given by a shareholder may be revoked before its exercise by:

BOID is soliciting the proxy for the special meeting on behalf of the BOID Board. BOID will bear the cost of solicitation of proxies from its shareholders. In addition to using the mail, BOID may solicit proxies in person or by telephone, email or facsimile, in each case without compensation. Banks, brokerage houses, other institutions, nominees, and fiduciaries will be requested to forward their proxy soliciting material to their principals and obtain authorization for the execution of proxies. BOID will, upon request, pay the standard charges and expenses of banks, brokerage houses, other institutions, nominees, and fiduciaries for forwarding proxy materials to and obtaining proxies from their principals.

Voting in Person at the Special Meeting

BOID common shares held directly in your name as the shareholder of record may be voted in person at the special meeting. If you choose to vote your BOID common shares in person, please bring the enclosed proxy

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card or proof of identification. Even if you plan to attend the special meeting, we recommend that you vote your shares of BOID common stock in advance as described above so that your vote will be counted if you later decide not to attend the special meeting.

If your shares are registered in “street name” in the name of a broker or other nominee and you wish to vote at the special meeting, you will need to obtain a legal proxy from your bank or brokerage firm. Please consult the voting form sent to you by your bank or broker to determine how to obtain a legal proxy in order to vote at the meeting.

The BOID Proposals

Proposal 1: Merger Proposal

BOID is asking its shareholders to approve the merger agreement. For a detailed discussion of the terms and conditions of the merger agreement, please see the section entitled “The Merger.” BOID shareholders should read this proxy statement/prospectus, including any documents incorporated in this proxy statement/prospectus by reference, and its annexes, carefully and in their entirety for more detailed information concerning the merger agreement and the merger. A copy of the merger agreement is attached to this proxy statement/prospectus as Appendix A.

As discussed in the section entitled “Background of and Reasons for the Merger,” after careful consideration, the BOID Board approved the execution, delivery and performance of the merger agreement and the transactions contemplated by it, including the merger, and determined the merger to be fair and in the best interests of BOID and the BOID shareholders.

Required Vote

Approval of the proposal to approve the merger agreement requires the affirmative vote of at least a majority of the outstanding shares of BOID’s common stock entitled to vote. If you mark “ABSTAIN” on your proxy card, fail to submit a proxy card or fail to vote by mail, by telephone, via the Internet, or in person at the special meeting, or are a “street name” holder and fail to instruct your bank, broker, or other nominee how to vote, it will have the same effect as votes against the merger proposal.

The approval of the merger by holders of BOID common shares is a condition to the completion of the merger.

The BOID Board recommends that BOID shareholders vote “FOR” the proposal to approve the merger agreement.

Proposal 2: Approval of Amendment to BOID’s Articles of Incorporation to Increase the Maximum Size of BOID’s Board of Directors from Nine to Eleven

The BOID Board has adopted, subject to shareholder approval, an amendment to BOID’s Articles of Incorporation to increase the maximum size of the BOID Board from nine directors to eleven directors.

If the amendment is adopted, it will become effective upon filing the Articles of Amendment with the Secretary of State of the State of Idaho, which BOID intends to file immediately after receipt of shareholder approval.

BOID’s current Articles of Incorporation provide that the number of directors constating the BOID Board shall not be less than five nor more than nine. Within this range, the BOID Board is authorized to fix the exact number of directors from time to time as provided in BOID’s bylaws. In an effort to bring additional perspectives to the BOID Board and to improve corporate governance the BOID Board previously increased the size of the BOID Board, consistent with BOID’s bylaws in effect at the time. BOID is thus seeking approval of the amendment to its Articles of Incorporation in order to synchronize the Articles of Incorporation with BOID’s bylaws.

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The text of the amendment to the Articles of Incorporation is as follows:

“ARTICLE IX. The number of directors constituting the Board of Directors of the corporation shall not be less than five nor more than eleven, with the exact number established by resolution adopted from time to time by the Board of Directors.”

Required Vote

Approval of the proposal to amend BOID’s Articles of Incorporation requires the affirmative vote of at least a majority of the outstanding shares of BOID’s common stock entitled to vote. If you mark “ABSTAIN” on your proxy card, fail to submit a proxy card or fail to vote by mail, by telephone, via the Internet, or in person at the special meeting, or are a “street name” holder and fail to instruct your bank, broker, or other nominee how to vote, it will have the same effect as votes against the merger proposal.

The BOID Board recommends that BOID shareholders vote “FOR” the proposal to amend BOID’s Articles of Incorporation.

Proposal 3: Adjournment Proposal

BOID is asking its shareholders to approve the adjournment of the BOID special meeting to another date and place if necessary or appropriate to solicit additional votes in favor of the merger proposal if there are insufficient votes at the time of such adjournment to approve the merger proposal.

If, at the BOID special meeting, an insufficient number of BOID common shares are present in person or represented by proxy and voting in favor of the merger proposal, BOID will move to adjourn the BOID special meeting to enable the BOID Board to solicit additional proxies for approval of the merger proposal. If the BOID shareholders approve the adjournment proposal, BOID may adjourn the BOID special meeting and use the additional time to solicit additional proxies, including the solicitation of proxies from BOID shareholders who have previously voted. If the date of the adjournment is not announced at the BOID special meeting or a new record date is fixed for the adjourned meeting, a new notice of the adjourned meeting will be given to each shareholder of record entitled to vote at the adjourned meeting and to all holders of BOID Class B non-voting common shares.

Required Vote

Approval of the adjournment proposal requires that the number of votes cast in favor of the proposal exceed the votes cast opposing the proposal. If you mark “ABSTAIN” on your proxy card, fail to submit a proxy card or fail to vote by mail, by telephone, via the Internet, or in person at the BOID special meeting, or are a “street name” holder and fail to instruct your bank, broker, or other nominee how to vote, it will have no effect on the adjournment proposal.

The BOID Board recommends that BOID shareholders vote “FOR” the adjournment proposal.

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BACKGROUND OF AND REASONS FOR THE MERGER

Background of the Merger

As part of its ongoing strategic planning and efforts to enhance shareholder value, the BOID Board and executive management regularly review and assess BOID’s strengths, weaknesses, strategic opportunities and challenges, in an ever changing and more complex operating environment. The BOID Board evaluated the prospects for continued organic growth and profitability, particularly in light of the difficulties operating as an independent community bank under current economic, regulatory and competitive conditions. Like many other banks, BOID has experienced increasing costs related to regulatory compliance, product development and personnel, in order to maintain compliance and remain competitive with bank and non-bank competitors, including financial technology companies. The BOID Board has also monitored the changing community banking landscape in the region, including the decline in potential buyers who could execute on a transaction that would be appealing to BOID.

Randall M. Chesler, President and Chief Executive Officer of Glacier, and Jeffrey K. Newgard, President and Chief Executive Officer of BOID, have lengthy careers in the financial institutions industry and have known each other professionally for several years. Over the years Messrs. Chesler and Newgard have periodically engaged in informal discussions about the organizations and the potential for strategic opportunities in the future.

Given the changing community banking landscape in the region, regulatory compliance burdens, rising information technology costs, and challenges for shareholders seeking liquidity arising from the limited trading market in BOID stock, the BOID Board considered strategic alternatives that could address these challenges. In reviewing its alternatives, the BOID Board considered the best ways to maximize shareholder value, maximize the opportunities for BOID’s employees and secure the Bank’s long-term ability to serve its customers and communities. The BOID Board carefully considered various strategic alternatives, including: (i) continued organic growth, which would be limited by BOID’s capital resources; (ii) growth through the acquisition of smaller institutions, which would be challenging given the lack of viable attractive targets, BOID’s limited capital resources and the relative illiquidity of BOID’s stock; or (iii) merging with a larger bank with more resources to support continued strong financial performance, provide BOID shareholders with greater liquidity, and better support the customers and communities the Bank serves. In considering these alternatives, the BOID Board viewed a sale to a larger financial institution as the alternative that best achieved its strategic objectives. Likewise, the BOID Board and management continued to pursue organic growth while undertaking strategic initiatives that would maximize the attractiveness of BOID to potential acquirors.

While the BOID Board was considering BOID’s future, BOID was approached in January 2024 by a credit union (the “Credit Union”) interested in acquiring the assets of the Bank. The BOID Board met in executive session with MJC Partners on January 16, 2024, to discuss the Credit Union’s proposal, other strategic alternatives, and continued independence. The BOID Board carefully considered the proposal at hand and decided it was in the best interest of BOID to explore a potential transaction with limited but capable acquirers in addition to exploring the Credit Union’s proposal. Based on previous conversations that BOID had with Glacier and another potential bank acquiror (the “Other Bank Acquiror”), BOID invited both Glacier and the Other Bank Acquiror to, concurrently with the Credit Union, consider a transaction with BOID in part to validate the pricing indication received from the Credit Union. As such, BOID had not been actively seeking a buyer at that time but because it was approached by the Credit Union, the BOID Board concluded it was in the best interests of BOID and its shareholders to engage with other known acquirers in the western United States.

At a meeting of Glacier’s board of directors (the “Glacier Board”) held on February 1, 2024, representatives from Glacier’s financial advisor D.A. Davidson & Co. (“D.A. Davidson”) provided a franchise overview of BOID, the Bank, and their operations that included discussion of the possible strategic fit of BOID’s operations with Glacier’s.

Glacier and BOID entered into a confidentiality agreement effective as of February 15, 2024, and BOID thereafter provided Glacier certain high level financial information with respect to BOID and the Bank.

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Soon after the BOID board meeting, on February 19, 2024, BOID formally engaged MJC Partners to serve as its financial advisor in connection with any transaction.

In early March, 2024, the Other Bank Acquiror withdrew from the process of considering a transaction as it was not able to meet BOID’s pricing expectations. On March 4, 2024, Glacier provided BOID with an indication of interest letter (the “Glacier March LOI”), and the Credit Union provided a letter of intent on March 5, 2024 (the “CU March LOI”), with pricing consistent with the pricing indication it had provided in January 2024.

BOID did not act on Glacier’s March LOI and it expired unexecuted on March 8, 2024. Glacier’s valuation did not meet the BOID Board’s expectations and was lower than the price offered by the Credit Union. BOID then discussed with its outside legal counsel whether the proposed credit union transaction was permissible and likely to receive required regulatory approvals on acceptable timelines, as well as potential execution risk in a transaction with a credit union. The BOID Board met on March 12, 2024, to discuss the CU March LOI with representatives of the Credit Union. On March 18, 2024, BOID executed the CU March LOI.

BOID then held additional discussions with its outside legal counsel and with the Director of the Idaho Department of Finance regarding the permissibility of a bank-credit union transaction in the weeks that followed. Those discussions, along with industry sentiment against bank-credit union transactions (and, as a result, the potential for industry groups to oppose the transaction), raised questions as to whether a transaction with the Credit Union would receive required regulatory approvals in a timely matter, or at all.

BOID held a special board meeting on April 10, 2024, to discuss the Director of the Idaho Department of Finance’s assessment of the permissibility of a bank-credit union transaction as well as feedback received from industry representatives and lobbyists. Also on April 10, 2024, due to the increasingly significant uncertainty regarding the likelihood of a transaction with the Credit Union being consummated, BOID terminated the CU March LOI with the expectation that dialogue with the Credit Union would stay open as BOID sought clarity from the Idaho Department of Finance on whether a bank-credit union transaction could receive the requisite regulatory approvals. BOID continued having its dialogue with the Idaho Department of Finance during the summer of 2024. BOID management also had intermittent conversations with Glacier’s senior management regarding its possible interest in a transaction without engaging in additional pricing discussions.

BOID met with MJC Partners on August 6, 2024, to discuss financial information from January 2024 that had been presented to the Credit Union and to Glacier at that time. Because BOID’s performance had exceeded expectations, it was requested that Brian Kouhdari, Executive Vice President, Chief Financial Officer and Cashier of BOID and the Bank, update the previously provided financial information; this updated information was provided to Glacier and to the Credit Union’s financial advisor on August 15, 2024. BOID management met virtually with Glacier management on September 6, 2024, to review BOID’s 2024 performance through August and to discuss BOID’s updated financial information.

On September 4, 2024, Glacier’s executive management team and D.A. Davidson met with the Glacier Board to provide an update on BOID’s financial performance, review market trends and discuss potential next steps regarding a transaction with BOID.

Glacier provided BOID with an updated indication of interest letter on October 4, 2024 (the “Glacier October LOI”). Around that time Mr. Newgard had a call with the Credit Union’s Chief Executive Officer to discuss the Credit Union’s continued interest in a transaction with BOID. The meeting ended with the Credit Union agreeing to provide BOID’s updated financial information to its financial advisor and the Credit Union provided an updated letter of intent to BOID on October 16, 2024 (the “CU October LOI”).

During this time BOID and Glacier, in consultation with their respective financial advisors, negotiated the terms of a potential transaction. BOID and Glacier held a financial diligence call on October 10, 2024, to discuss financial performance and related information. Following the call, on October 12, 2024, Glacier submitted a revised version of the Glacier October LOI with improved deal terms for BOID.

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The BOID Board held a special meeting on October 17, 2024, to discuss the proposals from Glacier and the Credit Union. At the meeting, the BOID Board reviewed the proposals and recognized that both were competitive, and, although Glacier’s pricing was slightly lower, voted to approve Glacier’s October LOI, as revised, and to pursue continued negotiations with Glacier given the lower execution risk of a transaction with Glacier, Glacier’s unique community banking model, the potential upside in Glacier’s stock price, the tax-free nature of an all stock merger transaction, and the opportunity for BOID and its shareholders to benefit from its earnings to close. BOID and Glacier continued to negotiate the terms of the Glacier October LOI and on October 18, 2024, Glacier provided BOID with a final version of the Glacier October LOI that included a 90-day exclusivity period. BOID executed the LOI that same day.

BOID informed the Credit Union on October 21, 2024, of its intent to not pursue a transaction with the Credit Union.

In response to a diligence request provided by Glacier, BOID provided Glacier a significant amount of information and legal documentation regarding its business operations and assets. On or about November 6, 2024, Glacier commenced its diligence regarding BOID, the Bank and their operations and assets, including loan portfolio, products and services, legal and regulatory compliance, and properties, among other matters. Concurrently with Glacier’s diligence, Miller Nash, legal counsel to Glacier, prepared and on December 10, 2024, presented to Otteson Shapiro, legal counsel to BOID, an initial draft of a plan and agreement of merger. Glacier continued its diligence review and the parties, through their legal counsel, negotiated the terms of the definitive agreement through early January 2025. In late December 2024 and early January 2025, Miller Nash presented, and together with Otteson Shapiro further negotiated the terms of, noncompetition and voting agreements with BOID’s directors and, with respect to the voting agreement, certain holders of greater than 5% of the BOID stock and transitional employment agreements with Messrs. Newgard and Kouhdari.

During this time, the Glacier Board received updates on the progress of the diligence review and the status of the proposed merger transaction from Glacier’s senior management and representatives of D.A. Davidson, including at regular board meetings held on October 30, 2024, and December 30, 2024.

On January 9, 2025, Glacier’s executive leadership team met to review the results of its diligence review of BOID and the Bank and, after discussion of findings and questions raised, provided preliminary approval for a transaction and approved presentation of the proposed transaction to the Glacier Board.

On January 13, 2025, the Glacier Board held a special meeting to consider the proposed merger with BOID. Glacier’s executive leadership team, other members of senior management, and representatives of D.A. Davidson and Miller Nash attended the meeting at the invitation of the Glacier Board. The Glacier Board was provided with a set of meeting materials in advance of the meeting, including substantially final drafts of the merger agreement, voting and noncompetition agreements, and transitional employment agreements, together with a comprehensive summary of management’s due diligence review of BOID. Miller Nash discussed with the directors their fiduciary duties under applicable law. Members of Glacier’s executive and senior management team and representatives of Miller Nash and D.A. Davidson then reviewed the due diligence process and findings in detail and responded to questions from directors. D.A. Davidson then reviewed the financial aspects of the proposed transaction, including the key financial terms of the proposed merger, and Miller Nash proceeded to review in detail with the Glacier Board the other material terms of the merger agreement and related transaction documents. After considering the proposed terms of the merger agreement and other transaction documents, and taking into consideration the matters discussed, the Glacier Board determined that the merger was in the best interests of Glacier and its shareholders, and unanimously approved the execution, delivery and performance of the merger agreement and the transactions contemplated by it, including the merger.

Also on January 13, 2025, the BOID Board held a special meeting to review and consider the proposed merger with Glacier. At the meeting, representatives of Otteson Shapiro explained the terms of the merger agreement and related transaction documents, and representatives of MJC Partners reviewed the financial aspects

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of the proposed merger and responded to questions by the BOID Board. Additionally, MJC Partners delivered its opinion (commonly referred to as the “fairness opinion”) to the effect that, as of such date and subject to the assumptions, qualifications and limitations set forth in its opinion, the consideration to be paid to BOID was fair, from a financial point of view, to the holders of BOID common stock. After further discussion among the directors and BOID’s advisors, including with respect to the factors described in “Reasons for the Merger — BOID,” the BOID Board unanimously determined that the merger and the merger agreement were advisable, and in the best interests of, BOID and its shareholders and unanimously approved the merger agreement, subject to shareholder and regulatory approvals, and related actions and recommended the adoption and approval of the merger agreement and transactions to BOID’s shareholders.

The parties entered into the merger agreement on January 13, 2025, and on that day, Glacier issued a press release announcing the merger transaction.

Reasons for the Merger – BOID

At a meeting held on January 13, 2025, the BOID Board determined that the terms of the merger agreement were in the best interests of BOID and its shareholders and recommended that BOID’s shareholders vote for approval of the merger agreement. In the course of reaching this determination and related decision to approve the merger agreement, the BOID Board evaluated the merger and the merger agreement in consultation with BOID’s financial advisor and legal counsel. In reaching its determination, the BOID Board considered a number of factors. Such factors also constituted the reasons that the BOID Board determined to approve the merger agreement and to recommend that BOID shareholders vote in favor of the merger agreement.

The following discussion of the information and factors considered by the BOID Board is not intended to be exhaustive, but, rather, includes the material factors considered by the BOID Board. In reaching its decision to approve the merger agreement, the merger of the Bank into Glacier Bank and the other transactions contemplated by the merger agreement, the BOID Board did not quantify or assign any relative weights to the factors considered, and individual directors may have given different weights to different factors. The BOID Board considered all these factors as a whole and overall considered the factors to be favorable to, and support, its determination to approve the merger agreement. In reaching its decision to approve the merger agreement, the BOID Board considered the following:

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The BOID Board also considered a number of uncertainties and risks in its deliberations concerning the transactions contemplated by the merger agreement, including the following:

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Opinion of BOID’s Financial Advisor

BOID engaged MJC Partners to act as its financial advisor and to provide an opinion of the fairness, from a financial point of view to the holders of BOID common shares of the consideration to be paid to BOID in the proposed merger.

The BOID Board selected MJC Partners based upon its reputation, its knowledge of financial institutions and its experience as a financial advisor in mergers and acquisitions transactions of financial institutions similar to the transaction contemplated and referenced herein. BOID imposed no limitations on MJC Partners’ investigations or the procedures it followed to render its opinion.

MJC Partners acted as an independent financial advisor to the BOID Board in connection with the proposed merger and participated in certain negotiations leading to the execution of the merger agreement. At the January 13, 2025 meeting, at which BOID’s Board evaluated the merger and the merger agreement, MJC Partners delivered to the BOID Board its oral opinion, which was subsequently confirmed in writing on January 13, 2025, to the effect that, as of such date, the merger consideration to be paid to BOID pursuant to the merger agreement is fair, from a financial point of view, to the holders of BOID common shares. This proxy statement/prospectus summary of the MJC Partners opinion is qualified in its entirety by reference to the full text of the opinion. The full text of the opinion of MJC Partners, dated January 13, 2025, which describes the procedures followed, assumptions made, matters considered and limitations on the review undertaken, is attached hereto as Appendix C. BOID shareholders should read this opinion in its entirety.

MJC Partners’ opinion is directed only to the fairness, from a financial point of view, of the consideration to be paid to BOID in the proposed merger, and, as such, does not constitute a recommendation to any BOID shareholder as to how the shareholder should vote at the special meeting. The summary of the opinion of MJC Partners set forth in this proxy statement/prospectus is qualified in its entirety by reference to the full text of the opinion.

The following summary of the analyses performed by MJC Partners is not a complete description of the analyses performed by MJC Partners to render its fairness opinion and is not a complete description of the

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presentation made by MJC Partners to the BOID Board. MJC Partners did not attribute any particular weight to any analysis and factor considered by it, but rather made qualitative judgments about the significance and relevance of each analysis and factor. MJC Partners believes that its analyses and the following summary must be considered as a whole, and that selecting portions of the analyses without considering all factors could create an incomplete account of its analyses and its fairness opinion.

To carry out its analyses and to render its opinion concerning the fairness of the per share merger consideration, MJC Partners, among other things:

MJC Partners also took into account its assessment of general economic, market and financial conditions and its experience in other transactions as well as its knowledge of the banking industry and its general experience in securities valuations.

Without independent verification, MJC Partners assumed the accuracy and completeness of the financial and other information and representations contained in the materials provided by BOID and in discussions with BOID. MJC Partners assumed that financial forecasts, including, without limitation, the projections regarding under-performing and nonperforming assets and net charge-offs were reasonably prepared on a basis reflecting best currently available information and judgments of BOID, and that the forecasts will be realized in the amounts and at the times contemplated thereby. MJC Partners did not evaluate the loan and lease portfolio to assess the adequacy of the allowances for losses, did not conduct a physical inspection of any properties or facilities, did not review individual credit files, and did not make an independent evaluation or appraisal of any properties, assets, or liabilities of BOID or Glacier, or any of their respective subsidiaries and MJC Partners was not furnished with any such evaluations or appraisals.

MJC Partners assumed that the merger will be consummated substantially in accordance with the terms set forth in the merger agreement. MJC Partners further assumed that the merger will be accounted for as a purchase under generally accepted accounting principles. MJC Partners assumed that the merger is, and will be, in compliance with all laws and regulations that are applicable to BOID and Glacier.

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MJC Partners reviewed the financial terms of the proposed merger. Pursuant to the terms of the merger agreement, at the effective time of the merger each BOID common share issued and outstanding immediately prior to the effective time of the merger, except for certain shares as set forth in the merger agreement, shall be converted into the right to receive, without interest, 1.1000 shares of Glacier common stock.

MJC Partners utilized an implied purchase price per share of $56.65 per outstanding BOID common share, or approximately $265.7 million in the aggregate (inclusive of the implied value of outstanding BOID restricted stock units, in the money stock options, and stock appreciation rights for BOID), based on the 1.1000x exchange ratio in the proposed merger and the 20-day VWAP of Glacier’s common stock price as of January 8, 2025. Based upon financial information for BOID as of or for the last twelve months (“LTM”) ended September 30, 2024, and the 20-day VWAP of Glacier’s common stock on January 8, 2025, MJC Partners calculated the following implied transaction metrics:

Present Value

Using BOID’s projected earnings and tangible book value for years ending December 31, 2024 through December 31, 2028, based on BOID guidance, MJC Partners estimated the terminal value of BOID’s common stock as a multiple of tangible book value (“TBV”) and as a multiple of earnings per share (“EPS”). MJC Partners discounted the terminal values back to present value using a range of discount rates. For terminal values at the end of the fifth year, MJC Partners performed two analyses, one assuming a trading multiple range from 1.43x to 1.63x times projected tangible book value per share (“TBVPS”), and the other assuming a trading multiple range from 11.8x to 15.8x times projected earnings per share. MJC Partners calculated the present value of these terminal amounts based on discount rates ranging from 9.7% to 11.7%. These rates and values were chosen to reflect different assumptions regarding the required rates of return of holders or prospective buyers of BOID’s common stock. Based on the present value analysis for BOID’s projected earnings per share and tangible book value per share on a standalone basis; MJC Partners arrived at a range of implied values per share of BOID stock of $42.90 to $63.22.

Comparable Company Analysis

MJC Partners used publicly available information to compare selected financial information for BOID with a group of publicly traded financial institutions. The peer group included banks and thrifts, headquartered in the Western, Southwestern, and Midwestern regions of the United States (comprised of Alaska, Arizona, California, Colorado, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Mexico, North Dakota, Ohio, Oklahoma, Oregon, South Dakota, Texas, Utah, Washington, Wisconsin, and Wyoming) with total assets between $750 million and $2.5 billion, listed on a publicly traded major exchange (defined as NASDAQCM, NASDAQGM, NASDAQGS, NYSE, and NYSEAM). Merger targets, ethnic focused banks, and banks with outlier pricing multiples were excluded. (the “BOID Peer Group”). The BOID Peer Group consisted of the following financial institutions:

First Savings Financial Group, Inc.

Eagle Bancorp Montana, Inc.

Ames National Corporation

Finward Bancorp

CF Bankshares Inc.

Oak Valley Bancorp

Middlefield Banc Corp.

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Citizens Community Bancorp, Inc.

Bank7 Corp.

Plumas Bancorp

Landmark Bancorp, Inc.

Ohio Valley Banc Corp.

Richmond Mutual Bancorporation, Inc.

BankFinancial Corporation

SB Financial Group, Inc.

United Security Bancshares

First Capital, Inc.

Summit State Bank

United Bancorp, Inc.

MJC Partners compared publicly available information for BOID with the BOID Peer Group as of or for the most recent quarter available as of September 30, 2024 and market pricing as of January 8, 2025. The table below outlines the information available for BOID compared to the 25^th percentile, median, and 75^th percentile of the BOID Peer Group:

1 ROATCE defined as Return on Average Tangible Common Equity

MJC Partners calculated the 25th percentile, median, and 75th percentile in terms of price as a multiple of tangible book value per share and price as a multiple of last-twelve-months earnings per share. MJC Partners applied these results to produce a range of implied values for BOID common shares ; applying a 50% weighting on price to tangible book value per share and 50% weighting to price as a multiple of last-twelve-months earnings per share to establish a range of value from the 25th percentile, median, and 75th percentile of the BOID Peer Group. MJC Partners utilized the 25th percentile, median, and 75th percentile multiples of the BOID Peer Group to determine a comparable price of BOID’s common shares. Based on this analysis of the BOID Peer Group’s pricing multiples, the implied price of BOID common stock shares, using the average of the two multiples, ranged from $25.16 to $34.94 as summarized in the table below:

Comparable Transactions

MJC Partners reviewed a group of comparable merger and acquisition transactions selected by MJC Partners consisting of whole commercial bank, savings bank, and thrift acquisition transactions located in the Western region of the United States (comprised of Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, Oregon, Washington, and Wyoming), announced on or after January 1, 2020 with publicly

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available pricing data and in which the target’s total assets were between $500 million and $2 billion at announcement of the transaction, excluding MOEs and strategic mergers, resulting in 13 transactions satisfying the criteria outlined below (“Comparable Transactions”):

MJC Partners compared publicly available information for BOID available as of or for the most recent quarter ending September 30, 2024 with the Comparable Transactions. The table below outlines the information available for BOID compared to the 25^th percentile, median, and 75^th percentile of the Comparable Transactions:

1 TCE / TA defined as Tangible Common Equity as a percentage of Tangible Assets

MJC Partners calculated the 25th percentile, median, and 75th percentile in terms of deal value as a multiple of tangible book value per share; deal value as a multiple of last-twelve-months earnings per share, and deal value minus tangible book value as a percent of core deposits. MJC Partners applied these results to produce a range of implied values for BOID common stock based on last-twelve-months earnings per share, tangible book value, and core deposits as of September 30, 2024; taking the average of deal value as a percent of last-twelve-months earnings per share, deal value as a percent of tangible book value, and deal value minus tangible book value as a percent of core deposits to establish a range of value from the 25th percentile, median, and 75th percentile. MJC Partners utilized the 25th percentile, median, and 75th percentile multiples to determine an implied value of BOID’s common stock. Based on this analysis of the selected transactions, the implied value of BOID common stock shares, using the average of the three multiples, ranged from $37.38 to $45.92 when all transactions were considered as summarized in the table immediately following.

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Proforma Merger Analysis

MJC Partners analyzed certain potential pro forma effects of the merger, based on the assumptions that (i) the merger is completed in the second calendar quarter of 2025 and (ii) each share of outstanding BOID common stock will be converted into the right to receive 1.1000 shares of Glacier common stock. MJC Partners also incorporated the following assumptions: (i) financial projections for BOID for the years ending December 31, 2024 through December 31, 2029 based on BOID management guidance; (ii) financial projections for Glacier for the years ending December 31, 2024 through December 31, 2029 based on analyst consensus projections and Glacier management guidance; (iii) Glacier purchase accounting adjustments consisting of (a) a credit mark on loans, (b) interest rate mark on loans, (c) core deposit intangibles, and (d) held-to-maturity securities mark; (iv) estimated annual cost savings based on estimates provided by Glacier and BOID management; and (v) estimated, pre-tax, one-time transaction costs based on estimates provided by Glacier and BOID management. The analysis indicated that the merger could be accretive to Glacier’s estimated earnings per share in the years ending 2025 through 2029 and immediately dilutive to estimated tangible book value. In connection with these analyses, MJC Partners considered and discussed with the BOID Board how the analysis would be affected by changes in the underlying assumptions, including the impact of final purchase accounting adjustments determined at the closing of the merger, and noted that the actual results achieved by the combined company may vary from projected results and the variations may be material.

Based on these analyses and other investigations and assumptions set forth in its opinion, MJC Partners determined that as of January 13, 2025, the consideration to be paid to BOID was fair, from a financial point of view to holders of BOID common shares.

MJC Partners’ Relationship

MJC Partners is acting as BOID’s financial advisor in connection with the merger. MJC Partners received a fee of $350,000 for rendering its written opinion to the BOID Board concerning the fairness to holders of BOID common shares of the consideration to be paid by Glacier in the merger. This fee is creditable against a transaction success fee in an amount equal to 1.75% of the aggregate consideration paid to BOID which MJC Partners will be entitled to receive if the merger is completed. In addition, BOID has agreed to indemnify MJC Partners against certain claims or liabilities arising out of MJC Partners’ engagement. In the two years prior to the issuance of this opinion, MJC Partners has had a material relationship with BOID for which MJC Partners received compensation.

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THE MERGER

The following is a brief description of the material aspects of the merger. There are other aspects of the merger that are not discussed below but that are contained in the merger agreement. You are being asked to approve the merger in accordance with the terms of the merger agreement, and you are urged to read the merger agreement carefully. The following summary is qualified in its entirety by reference to the complete text of the merger agreement, which is incorporated by reference into this proxy statement/prospectus and is attached to this proxy statement/prospectus as Appendix A.

Basic Terms of the Merger

The merger agreement provides for the merger of BOID with and into Glacier and, immediately thereafter, the merger of the Bank with and into Glacier Bank, Glacier’s wholly owned subsidiary.

In the merger, BOID shareholders who do not dissent will receive Glacier common stock for their BOID common shares, as described below. See “The Merger – Merger Consideration.”

The merger agreement is subject to a number of conditions that must be fulfilled in order to close. Those conditions include: approval by the shareholders of BOID, regulatory approvals, the continued accuracy of certain representations and warranties by both parties (subject to the materiality standards set forth in the merger agreement), and the performance by both parties of certain covenants and agreements. While Glacier and BOID believe that they will receive the necessary regulatory approvals for the merger, there can be no assurance that such approvals will be received or, if received, as to the timing of such approvals or as to the ability to obtain such approvals on satisfactory terms. See “The Merger – Conditions to the Merger” and “ – Regulatory Requirements.”

Merger Consideration

As of the effective date of the merger, all outstanding BOID shares (including each outstanding share of restricted stock and share to be issued upon settlement of RSUs and each outstanding BOID non-voting Class B share) will be converted into the right to receive 1.1000 Glacier shares. subject to possible adjustment as set forth below.

If the average closing price of Glacier common stock calculated in accordance with the merger agreement is less than $35.74, BOID may provide notice to Glacier of its intention to terminate the merger agreement, unless Glacier elects to increase, on a per-share basis, the number of shares of Glacier common stock to be issued in the merger, such that the total consideration value per share is equal to $35.74, in order to avoid termination of the agreement (or, in its discretion, Glacier may elect to include a fixed amount of cash per share, or a combination thereof).

Conversely, if the average closing price of Glacier common stock calculated in accordance with the merger agreement exceeds $53.60, Glacier may provide notice to BOID of its intention to terminate the merger agreement, unless BOID elects to accept a decrease, on a per-share basis, in the number of shares to be issued in the merger, such that the total consideration value per share is equal to $53.60, in order to avoid termination of the merger agreement. By voting to approve the merger agreement, BOID shareholders will give the BOID Board the authority to elect to cause BOID to accept a decrease, on a per-share basis, in the number of shares of Glacier common stock to be issued in the merger if the Glacier average closing price exceeds $53.60.

The per share stock consideration will be subject to reduction if the “BOID Closing Capital”, as determined in accordance with the merger agreement, is less than $122,126,000 (subject to specified adjustments) (the “Closing Capital Requirement”). In such event, the per share stock consideration will be reduced on a per share basis by an amount, rounded to the nearest thousandth, determined by dividing the negative differential between

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the BOID Closing Capital and the Closing Capital Requirement by the average daily closing price of Glacier common stock for the 20 trading days immediately preceding such date, and dividing that result by the number of BOID common shares outstanding at the effective time of the merger. See “The Merger – Calculation of BOID Closing Capital.”

If the BOID Closing Capital is in excess of $122,126,000, plus the amount of BOID Closing Capital attributable to the exercise of BOID Options after September 30, 2024, if any, BOID may, prior to the merger, declare and pay a special cash dividend to its shareholders in the aggregate amount of such excess.

Assuming for purposes of illustration only that the average closing price for Glacier common stock is $[   ] (which was the closing price of Glacier common stock on [   ], 2025) and no adjustments are made to the per share stock consideration, each of your BOID common shares would be exchanged for 1.1000 shares of Glacier common stock with a value equal to $[   ].

Calculation of BOID Closing Capital

“BOID Closing Capital” is defined in the merger agreement and is equal to an amount, estimated as of the closing of the merger, of BOID’s capital stock, surplus and retained earnings determined in accordance with accounting principles generally accepted in the United States (“GAAP”) on a consolidated basis, net of goodwill and other intangible assets, calculated in the same manner in which BOID’s consolidated tangible equity capital at September 30, 2024 was calculated, after giving effect to adjustments, calculated in accordance with GAAP, for accumulated other comprehensive income or loss as reported on BOID’s balance sheet. BOID Closing Capital will also reflect the accumulated income or loss related to the fair value of BOID’s held-to-maturity securities as calculated in the same manner as the accumulated other comprehensive income or loss shown on the Bank’s balance sheet for available-for-sale securities.

The BOID Closing Capital may be adjusted based on the estimated final amount of transaction-related expenses to be incurred by BOID, as determined and agreed upon between BOID and Glacier in accordance with the merger agreement. To the extent that such final transaction-related expenses do not equal $11,695,000, the amount of such difference, on an after-tax basis, will be reflected as a pro-forma adjustment to the BOID Closing Capital, reducing or increasing, as the case may be, the BOID Closing Capital.

Treatment of BOID Equity Awards

Under the terms of the merger agreement, holders of any BOID Options that may be exercised may provide notice of exercise of such BOID Options to BOID on or before the 30^th calendar day prior to the effective date of the merger (the “option exercise notice deadline”). Holders of BOID Options who exercise such BOID Options prior to the option exercise notice deadline will receive BOID common shares in accordance with the terms of the exercised BOID Options, and such BOID common shares will be converted into the right to receive the merger consideration in accordance with the terms of the merger agreement.

With respect to any BOID Options or SARs that remain outstanding and unexercised when the merger agreement becomes effective (the “effective time”), each such outstanding BOID Option or SAR under the BOID Stock Plans will be automatically canceled at the effective time, and the holders of BOID Options and SARs will be paid in cash an amount per share equal to the spread, if any, between (a) the product of the Glacier average closing price multiplied by the per share stock consideration and (b) the exercise price per share of such BOID Option or BOID SAR, net of any cash which must be withheld under applicable tax laws. Any BOID Option or SARs that has an exercise price per share that is equal to or greater than the amount described in (a) above will be cancelled without any payment.

With respect to any shares of restricted stock or RSUs that remain outstanding at the effective time, each outstanding share of restricted stock or RSU under the BOID Stock Plans will automatically vest, RSUs will be settled in stock, and each resulting BOID common share will have the right to receive the per share stock consideration and cash in lieu of fractional shares of BOID common shares.

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Fractional Shares

No fractional shares of Glacier common stock will be issued to any holder of BOID common shares in the merger. For each fractional share that would otherwise be issued, Glacier will pay cash in an amount equal to the fraction multiplied by the Glacier average closing price calculated as provided in the merger agreement. No interest will be paid or accrued on cash payable in lieu of fractional shares of Glacier common stock.

Effective Date of the Merger

Subject to the satisfaction or waiver of conditions to the obligations of the parties to complete the merger as set forth in the merger agreement, the effective date of the merger will be the date the merger becomes effective under the Montana Business Corporation Act (the “MBCA”) and the Idaho Business Corporation Act (the “IBCA”). Subject to the foregoing and the possible adjustment of the closing date as discussed under “—Closing Date” below, it is currently anticipated that the merger will be consummated during the second quarter of 2025.

Letter of Transmittal

Within five business days following the effective date of the merger, Glacier’s exchange agent will send a letter of transmittal to each holder of record of BOID common shares. This mailing will contain instructions on how to provide evidence of ownership in exchange for the merger consideration that the holder is entitled to receive under the merger agreement.

With the exception of any proposed dissenting shares, each BOID share certificate or uncertificated share will, from and after the effective date of the merger, be deemed to represent and evidence only the right to receive the merger consideration payable with respect to such certificate or uncertificated share. BOID shareholders must provide properly completed and executed letters of transmittal in order to effect the exchange of their BOID common shares for (i) evidence of issuance in book entry form representing Glacier common stock, and (ii) a check representing the amount of cash in lieu of fractional shares, if any.

Lost, Stolen or Destroyed Certificates

If a certificate for BOID common shares has been lost, stolen or destroyed, the exchange agent will be authorized to issue or pay the holder’s merger consideration (and cash in lieu of fractional shares, if any), if the holder provides Glacier with (i) satisfactory evidence that the holder owns the BOID common shares and that the certificate is lost, stolen or destroyed, (ii) any affidavit or security Glacier may require (including any bond that may be required by the exchange agent in accordance with its policies), and (iii) any reasonable additional assurances that Glacier or Glacier’s exchange agent may require.

Voting Agreements

BOID’s directors and executive officers (in their individual capacities as BOID shareholders) and certain significant shareholders (each, a “Shareholder”) have entered into a Voting Agreement and Irrevocable Proxy with Glacier, Glacier Bank, BOID, and the Bank, dated January 13, 2025 (the “Voting Agreement”). Under the Voting Agreement, each Shareholder agrees, among other things, to vote all shares of BOID common stock that he or she owns or controls in favor of approval of the merger agreement. The Voting Agreement also prohibits each Shareholder from selling, transferring, encumbering, or granting a proxy in respect of their shares prior to the termination of the Voting Agreement, subject to certain exceptions. As of the record date, the Shareholders under the Voting Agreement are collectively entitled to vote a total of 1,603,411 BOID common shares, representing approximately [   ]% of all outstanding BOID common shares entitled to vote at the special meeting. The Voting Agreement also provides that each Shareholder will vote their shares in favor of any proposal to adjourn the special meeting if there are not sufficient votes to approve the merger agreement. Any such vote to adjourn, if necessary, would occur at the special meeting.

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Appraisal Rights

Under the Idaho Statutes, BOID shareholders (including holders of BOID non-voting Class B shares) have the right to dissent from the merger and to receive payment in cash for the “fair value” of their shares of BOID common stock.

BOID shareholders electing to exercise appraisal rights must comply with the provisions of applicable Idaho laws in order to perfect their rights. The following is intended only as a brief summary of the material provisions of the procedures that a BOID shareholder must follow in order to dissent from the merger and perfect appraisal rights. This summary, however, is not a complete statement of all applicable requirements and is qualified in its entirety by reference to the Idaho appraisal rights laws, the full text of which is set forth in Appendix B to this document.

A shareholder who wishes to exercise appraisal rights must:

A shareholder wishing to deliver a notice asserting appraisal rights should hand deliver or mail the notice to the following address:

Bank of Idaho Holding Co.

350 Memorial Drive

Suite 200

Idaho Falls, Idaho 83402

ATTN: Shanon Taylor, Corporate Secretary

A shareholder who wishes to exercise appraisal rights generally must dissent with respect to all of the shares the shareholder owns or over which the shareholder has the power to direct the vote. However, if a record shareholder is a nominee for several beneficial shareholders, some of whom wish to dissent and some of whom do not, then the record holder may dissent with respect to all the shares beneficially owned by any one person by notifying BOID in writing of the name and address of each person on whose behalf the record owner asserts appraisal rights. A beneficial shareholder may assert appraisal rights directly by submitting to BOID the record shareholder’s written consent and by dissenting with respect to all the shares of which the shareholder is the beneficial shareholder or over which the shareholder has the power to direct the vote.

A shareholder who does not, prior to the special shareholders’ meeting, deliver to BOID a written notice of the shareholder’s intent to demand payment for the shares will lose the right to exercise appraisal rights. In addition, any shareholder electing to exercise appraisal rights must either vote against the merger or abstain from voting.

If the merger is completed, Glacier (as the surviving corporation) will, within 10 days after the effective date of the merger, deliver a written notice to all BOID shareholders who properly gave notice of their intent to exercise appraisal rights. The notice will, among other things:

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A shareholder who sent a notice as described above must demand payment, complete and return the certification form, and deposit the shareholder’s certificates in accordance with the terms of the notice. A shareholder who demands payment and deposits the shareholder’s certificates loses all other rights of a shareholder unless the shareholder withdraws by the date set forth above.

A shareholder who does not demand payment by returning the signed form, fails to certify beneficial ownership on the form, or does not deposit the shareholder’s certificates if required, each by the date set forth in the notice, is not entitled to payment for such shareholder’s shares.

The Idaho Statutes provide that Glacier (as the surviving corporation) must pay any dissenter who has complied with the requirements summarized above the “fair value” of the shareholder’s shares plus interest from the effective date of the merger within 30 days after the date Glacier sets for receipt of such form. With respect to a dissenter who did not beneficially own shares of BOID prior to the public announcement of the merger or certify that the shareholder beneficially owned such shares, Glacier is not required to make the payment until the dissenter has agreed to accept the payment in full satisfaction of the dissenter’s demands. “Fair value” means the value of the shares immediately before the effective date of the merger, using customary and current valuation concepts and techniques generally employed for similar businesses under similar circumstances and without any discount for lack of marketability or minority status. Investment banker opinions as to the fairness, from a financial point of view, of the consideration payable in a transaction such as the merger are not opinions as to, and do not address, “fair value” under the Idaho Statutes.

Glacier’s payment to a dissenting shareholder will be accompanied by BOID’s financial statements, including a balance sheet, income statement, and cash flow as of the end of the most recent fiscal year, as well as interim financial statements (if any); a statement of Glacier’s estimate of the fair value of the shares; and a statement that shareholders who complied with the notice requirements (including returning the signed form to Glacier) have the right to demand further payment if such shareholder is dissatisfied with the payment, and if a shareholder does not demand further payment within 30 days of receiving payment, the shareholder will be deemed to have accepted the payment amount in full satisfaction of Glacier’s obligations.

Within 30 days of Glacier’s payment (or offer of payment in the case of shares acquired after public announcement of the merger) to a dissenting shareholder, a dissenter dissatisfied with Glacier’s estimate of the

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fair value may notify Glacier of the dissenter’s own estimate of the fair value and demand payment of that amount. If Glacier does not accept the dissenter’s estimate and the parties do not otherwise settle on a fair value, then Glacier must, within 60 days of receiving the estimate and demand, petition a court to determine fair value.

No BOID shareholder who has validly exercised its appraisal rights pursuant to Chapter 30-29-1300 of the Idaho Statutes with respect to its BOID common shares will be entitled to receive any portion of the merger consideration with respect to the dissenting shares owned by such dissenting BOID shareholder unless and until such dissenting BOID shareholder fails to perfect or otherwise waives, withdraws or loses its appraisal rights under the Idaho Statutes. Each dissenting BOID shareholder will be entitled to receive only the payment resulting from the procedures set forth in 30-29-1300 of the Idaho Statutes with respect to the dissenting shares owned by such dissenting BOID shareholder.

In view of the complexity of the Idaho statutes governing appraisal rights, BOID shareholders who wish to dissent from the merger and pursue appraisal rights should consult their legal advisors.

The failure of a BOID shareholder to comply strictly with the Idaho statutory requirements will result in a loss of appraisal rights. A copy of the relevant statutory provisions is attached as Appendix B. You should refer to Appendix B for a complete statement concerning appraisal rights and the foregoing summary of such rights is qualified in its entirety by reference to Appendix B.

Conditions to the Merger

Completion of the merger is subject to various conditions. No assurance can be provided as to whether these conditions will be satisfied or waived by the appropriate party. Accordingly, there can be no assurance that the merger will be completed.

Certain customary conditions must be satisfied, or specified events must occur, before the parties will be obligated to complete the merger. Each party’s obligations under the merger agreement are conditioned on satisfaction by the other party of conditions applicable to them.

Additionally, either Glacier or BOID may terminate the merger if certain conditions applicable to the other party are not satisfied or waived. Those conditions are discussed below under “The Merger –Termination of the Merger Agreement.”

Either Glacier or BOID may waive any conditions applicable to its obligations, except those that are required by law (such as receipt of regulatory approvals and BOID shareholder approval). Either Glacier or BOID may also grant extended time to the other party to complete an obligation or condition.

Covenants

The merger agreement contains numerous agreements between the parties regarding the handling of various matters before the merger. These agreements include:

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“No-Shop”/Board Recommendation Provisions

The merger agreement provides that, as of the signing of the merger agreement, BOID and the Bank must cease any existing activities, discussions or negotiations with any parties with respect to a third-party acquisition proposal and, except as otherwise permitted under the merger agreement, BOID and the Bank may not, and must direct and use their best efforts to cause their directors, officers, employees, agents and representatives not to:

Notwithstanding the immediately preceding provision, before BOID’s shareholders approve the merger, if BOID receives a written unsolicited acquisition proposal and the BOID Board determines in good faith and after consultation with independent legal counsel that (a) the proposal constitutes or is reasonably expected to result in a superior proposal and (b) the board’s fiduciary duties require BOID to engage in negotiations with, provide confidential information to, or have any discussions with, a person in connection with such proposal, then BOID may do so to the extent the board determines that failure to take such actions would result in a breach of the directors’ fiduciary duties under applicable law. In such event, prior to providing any confidential information, BOID must enter into a confidentiality agreement with the person on terms at least as favorable to BOID as its confidentiality agreement with Glacier. BOID must notify Glacier of any unsolicited acquisition proposal it receives.

The merger agreement provides that the BOID Board will recommend approval of the merger agreement to BOID’s shareholders, and will not withdraw, modify or qualify its recommendation, unless BOID receives a superior proposal and the BOID Board determines, in good faith and after consultation with its legal counsel, that it would be inconsistent with its fiduciary duties not to withdraw, modify or qualify its recommendation.

Representations and Warranties

BOID and Glacier have made certain customary representations and warranties to each other in the merger agreement relating to their businesses. The representations and warranties contained in the merger agreement were made only for purposes of such agreement and are made as of specific dates, were solely for the benefit of the parties to such agreement, and may be subject to limitations agreed to by the parties, including being

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qualified by knowledge, materiality or disclosures between the parties. These representations and warranties may have been made to allocate risk between the parties to the merger agreement instead of establishing these matters as facts, and are likely to be subject to standards of materiality that differ from the standard of materiality that an investor may apply when reviewing statements of factual information.

Amendment of the Merger Agreement

The merger agreement may be amended upon authorization of the boards of directors of the parties, whether before or after the special meeting of the shareholders of BOID. To the extent permitted under applicable law, the parties may make any amendment or supplement without further approval of BOID shareholders. However, after BOID shareholder approval, any amendment that would change the form or reduce the amount of consideration that BOID shareholders will receive in the merger would require further approval from BOID shareholders.

Termination of the Merger Agreement

The merger agreement contains several provisions entitling either Glacier or BOID to terminate the merger agreement under certain circumstances. The following briefly describes these provisions:

Lapse of Time. If the merger has not been consummated on or before October 31, 2025, then at any time after that date, either Glacier or BOID may terminate the merger agreement and the merger if the terminating party delivers to the other party written notice that its board of directors has voted in favor of termination; provided, however, if as of October 31, 2025, all required regulatory approvals have not been obtained, then the deadline for consummation of the merger will be extended to on or before January 31, 2026, if either Glacier or BOID notifies the other party in writing on or prior to October 31, 2025, of its election to extend such date.

Glacier Average Closing Price Less than $35.74. BOID may provide written notice to Glacier of its intent to terminate the merger agreement because the Glacier average closing price (as defined in the merger agreement) is less than $35.74. If BOID has provided notice of its intent to terminate the merger agreement because the Glacier average closing price is less than $35.74, Glacier may elect, within three business days of its receipt of such notice, to increase the number of Glacier shares to be issued in the merger (or, in its discretion, Glacier may elect to include a fixed amount of cash per share, or a combination thereof), calculated in the manner described above under “—Merger Consideration.”

If Glacier makes such election, no termination of the merger agreement will occur, and the merger agreement will remain in effect in accordance with its terms, except as the consideration has been adjusted.

Glacier Average Closing Price Greater than $53.60. By specific action of its board of directors, Glacier may terminate the merger agreement if the Glacier average closing price is greater than $53.60. If Glacier provides written notice of its intent to terminate the merger agreement because the Glacier average closing price is greater than $53.60, BOID may elect, within three business days of its receipt of such notice, to accept a decrease in the total number of Glacier shares, calculated in the manner described above under “—Merger Consideration.”

If BOID makes the election to accept such decrease in the number of Glacier shares to be issued, no termination of the merger agreement will occur, and the merger agreement will remain in effect in accordance with its terms, except that the total number of Glacier shares to be issued in the merger would decrease. As a result, the amount of Glacier common stock exchanged for each BOID common share would decrease. In prior merger transactions with similar adjustment rights, Glacier has exercised its right to terminate the merger agreement, and the seller in such prior merger transactions elected to accept a decrease in the number of Glacier shares issued in the merger.

Mutual Consent. The parties may terminate the merger agreement at any time before closing, whether before or after approval by BOID shareholders, by mutual consent if the board of directors of each party agrees to terminate by a majority vote of all of its members.

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No Regulatory Approvals. Either party may terminate the merger agreement if the regulatory approvals required to be obtained are denied, or if any such approval is subject to a condition or requirement not normally imposed in such transactions that would deprive Glacier of the economic or business benefits of the merger in a manner that is material relative to the aggregate economic business benefits of the merger to Glacier, subject to certain rights granted in the merger agreement to appeal any denial of such regulatory approval.

Breach of Representation or Covenant. Either party may terminate the merger agreement (so long as the terminating party is not then in material breach of any of its representations, warranties, covenants or agreements in the merger agreement in a manner that would entitle the other party not to consummate the merger) if there has been a breach of any of the covenants or obligations set forth in the merger agreement by the other party, which is not cured within 30 days following written notice to the party committing such breach, or which breach, by its nature, cannot be cured prior to the closing of the merger, subject to certain conditions.

Failure to Recommend or Obtain Shareholder Approval. Glacier may terminate the merger agreement if the BOID Board (i) fails to recommend to its shareholders approval of the merger, or (ii) modifies, withdraws or changes in a manner adverse to Glacier its recommendation to shareholders to approve the merger. Additionally, regardless of whether or not the BOID Board recommends approval of the merger to its shareholders, Glacier or BOID may terminate the merger agreement if BOID shareholders do not approve the merger.

Dissenting Shares. Glacier may terminate the merger agreement if holders of 10% or more of the outstanding BOID shares have properly given notice of their intent to assert appraisal rights under Idaho law.

Superior Proposal – Termination by BOID. BOID may terminate the merger agreement if the BOID Board determines in good faith that BOID has received a “Superior Proposal” (as defined in the merger agreement). This right is subject to the requirement that BOID may terminate the merger agreement only if BOID (i) has not materially breached its covenants regarding the initiation or solicitation of acquisition proposals from third parties and submission of the merger agreement to BOID shareholders; (ii) promptly following the delivery of such notice of termination to Glacier, BOID enters into a definitive acquisition agreement relating to such Superior Proposal, (iii) BOID has provided Glacier with at least ten days’ prior written notice (the “Notice Period”) that the BOID Board is prepared to accept a Superior Proposal and has given Glacier, if it so elects, an opportunity to amend the terms of the merger agreement during the Notice Period (and negotiated with Glacier in good faith with respect to such terms during the Notice Period) in such a manner as would enable the BOID Board to proceed with the merger without violating their fiduciary duties and (iv) simultaneously upon entering into such definitive acquisition agreement relating to the Superior Proposal, it delivers to Glacier the break-up fee described below.

Superior Proposal – Termination by Glacier. Glacier may terminate the merger agreement if an “Acquisition Event” (as defined in the merger agreement) has occurred.

Break-Up Fee

If the merger agreement is terminated because (i) the BOID Board fails to recommend shareholder approval of the merger agreement or modifies, or withdraws or changes its recommendation in a manner adverse to Glacier; or (ii) BOID terminates the merger agreement after receiving a Superior Proposal and Glacier declines the opportunity to amend the terms of the merger agreement to enable the BOID Board to proceed with the merger; or (iii) Glacier terminates the merger agreement if an Acquisition Event has occurred, then BOID will immediately pay Glacier a break-up fee of $8,000,000.

In addition, if the merger agreement is terminated (i) by Glacier for BOID’s breach of specified covenants set forth in the merger agreement or (ii) by Glacier due to the merger agreement not being approved by the BOID shareholders, and within 18 months after any such termination, BOID or the Bank enters into an agreement for, or publicly announces its intention to engage in, an Acquisition Event, or an Acquisition Event occurs, then

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BOID will promptly following such entry, announcement, or occurrence pay Glacier the break-up fee of $8,000,000.

Allocation of Costs Upon Termination

If the merger agreement is terminated (except under circumstances that would require the payment of a break-up fee) Glacier and BOID will each pay their own out-of-pocket expenses incurred in connection with the transaction.

Conduct Pending the Merger

The merger agreement provides that, until the merger is effective, the parties will conduct their respective business only in the ordinary and usual course. In that regard, the merger agreement provides that, unless the other party otherwise consents in writing, and except as required by applicable regulatory authorities, the parties will refrain from engaging in specified significant activities.

Bank Management and Operations After the Merger

Immediately following the merger of BOID with and into Glacier, the Bank will be merged with and into Glacier Bank. The former branches of the Bank will be integrated with Glacier Bank’s existing divisions operating in Idaho and Washington.

Employees and Employee Benefit Plans

The merger agreement provides that Glacier’s and Glacier Bank’s current personnel policies will apply to any employees of BOID or the Bank who remain employed following the closing of the merger. Such employees will be eligible to participate in all of the benefit plans of Glacier and/or Glacier Bank that are generally available to similarly situated employees of Glacier and/or Glacier Bank.

Current employees’ prior service with BOID and/or the Bank, as applicable, will constitute prior service with Glacier or Glacier Bank for all purposes with respect to employee benefit plans. Any current employees of BOID or the Bank who are not entitled to severance, change in control, or other payments at or in connection with the closing of the merger and are not offered a position by Glacier or retained by Glacier Bank for at least one year following the closing of the merger will receive severance payments in accordance with Glacier Bank’s severance policy in effect at the closing of the merger based on the number of such employee’s years of prior service with BOID and the Bank, as applicable, at the expense of Glacier.

Certain benefit and compensation plans, including the Bank of Idaho Holding Company Employee Stock Ownership Plan (the “ESOP”) and the Bank of Idaho 401(k) Plan (the “401(k)”), will be terminated in connection with the merger. Prior to the closing of the merger, BOID will adopt amendments to the ESOP and the 401(k) that provide that, contingent upon the closing of the merger: (a) the ESOP and 401(k) shall be terminated effective as of the day before the closing of the merger, (b) immediately prior to such termination, the ESOP and 401(k) shall be in compliance in all material respects with all applicable laws, (c) no new participants shall be admitted to the ESOP or 401(k) after the termination, (d) to the extent they are not already vested, the accounts of participants in the ESOP and 401(k) shall fully vest and be 100 percent non-forfeitable, and (e) the ESOP and 401(k) shall permit the entire balance of a participant’s account to be distributable following receipt of a determination by the Internal Revenue Service that termination of the ESOP or 401(k) does not adversely affect the ESOP’s or 401(k)’s tax-qualified status.

Interests of BOID Directors and Executive Officers in the Merger

Certain members of the BOID Board and the Bank’s Board of Directors and BOID’s and the Bank’s executive management may be deemed to have interests in the merger, in addition to their interests as

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shareholders of BOID generally. The BOID Board was aware of these interests and considered them, among other things, in approving the merger agreement.

Change in Control Payments Under Existing Agreement with BOID

BOID and the Bank previously entered into employment agreements or change in control agreements with certain executive officers of BOID and the Bank that provide for benefits and compensation payable in the event of a termination of employment following a change in control of BOID or the Bank, including: (1) an employment agreement with Jeff Newgard, President and Chief Executive Officer of BOID and the Bank, dated August 13, 2024 (the “Newgard Agreement”); and (2) an employment agreement with Brian Kouhdari, Executive Vice President, Chief Financial Officer and Cashier of BOID and the Bank, dated August 13, 2024 (the “Kouhdari Agreement”).

The Newgard Agreement. The Newgard Agreement contains change in control provisions under which, and subject to certain time periods and conditions precedent, Mr. Newgard would be entitled to receive a lump-sum severance payment in an amount equal to the sum of 30 months of his then-base salary, his then-earned incentive compensation, 2.5 times the highest average annual incentive received over the previous five years and payment of 18 months’ COBRA premiums. Mr. Newgard would be entitled to receive this payment if his employment is terminated without “Cause” or for “Good Reason” (each as defined in the Newgard Agreement) within six months after a change in control. Additionally, if Mr. Newgard’s employment is terminated without Cause or for Good Reason within 24 months after a change in control or if he is offered a position other than Chief Executive Officer of the Bank and President of BOID, he would be entitled to receive a lump-sum severance payment in an amount equal to 30 months of his then-base salary plus his then-earned incentive compensation, and continued insurance coverage for Mr. Newgard and his dependents for 18 months (or alternatively, a lump-sum payment in an amount equal to the total premiums required to maintain such coverage). In general, a change in control under the Newgard Agreement means: (1) the consummation of a merger or consolidation of the Bank and/or BOID with or into another entity, any corporate reorganization if the beneficial ownership of the resulting organization changes by more than 50%, or other reorganization in which Mr. Newgard does not retain his position as Chief Executive Officer of the Bank and President of BOID; (2) a change in the composition of the board of directors of the Bank in which the “Incumbent Board” (as such term is defined in the Newgard Agreement) ceases for any reason to constitute at least a majority of the board of directors of the Bank; or (3) the sale or other disposition of all or substantially all of the assets of BOID or the Bank. The merger as currently proposed would constitute a change in control under the Newgard Agreement.

The Kouhdari Agreement. The Kouhdari Agreement contains change in control provisions under which, and subject to certain time periods and conditions precedent, Mr. Kouhdari would be entitled to receive a lump-sum severance payment in an amount equal to the sum of 18 months of his then-base salary, his then-earned incentive compensation, 1.5 times the highest average annual incentive received over the previous five years and payment of 18 months’ COBRA premiums. Mr. Kouhdari would be entitled to receive this payment if his employment is terminated without Cause or for Good Reason “Cause” or for “Good Reason” (each as defined in the Kouhdari Agreement) within six months after a change in control. Additionally, if Mr. Kouhdari’s employment is terminated without Cause or for Good Reason, within 24 months after a change in control or if he is offered a position other than Chief Financial Officer of the Bank and Cashier of BOID, he would be entitled to receive a lump-sum severance payment in the amount equal to 18 months of his then-base salary plus his then-earned incentive compensation, and continued insurance coverage for Mr. Kouhdari and his dependents for 18 months (or alternatively, a lump-sum payment in an amount equal to the total cost of insurance premiums required to maintain such coverage). In general, a change in control under the Kouhdari Agreement means: (1) the consummation of a merger or consolidation of the Bank and/or BOID with or into another entity, any corporate reorganization if the beneficial ownership of the resulting organization changes by more than 50%, or other reorganization in which Mr. Kouhdari does not retain his position as Chief Financial Officer of the Bank and Cashier of BOID; (2) a change in the composition of the board of directors of the Bank in which the “Incumbent Board” (as such term is defined in the Kouhdari Agreement) ceases for any reason to constitute at

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least a majority of the board of directors of the Bank; or (3) the sale or other disposition of all or substantially all of the assets of BOID or the Bank. The merger as currently proposed would constitute a change in control under the Kouhdari Agreement.

The Newgard Agreement and the Kouhdari Agreement are being superseded in their entirety by the Closing Payment Agreements described below and no amounts are expected to be paid in respect of the Newgard Agreement or the Kouhdari Agreement.

Closing Payment Agreements

BOID and the Bank have entered into closing payment agreements with each of Messrs. Newgard and Kouhdari which are conditioned upon the closing of the merger (the “Closing Payment Agreements”). The Closing Payment Agreements provide that if each of Messrs. Newgard and Kouhdari remain employed with BOID and the Bank through the closing date of the merger, each will receive a lump-sum cash payment, less applicable tax withholdings, as follows: (1) Mr. Newgard, $1,474,235; and (2) Mr. Kouhdari, $636,152. The Closing Payment Agreements provide, however, that, if such amount, together with any other payments or rights that the executive officer may be entitled to receive, would constitute an “excess parachute payment” under applicable provisions of the Internal Revenue Code, the payment pursuant to the Closing Payment Agreements will be reduced to the extent necessary to ensure that no portion of such payment will be subject to the excise tax imposed on excess parachute payments. Amounts received pursuant to the Closing Payment Agreements are in lieu of any amounts to which Messrs. Newgard and Kouhdari were entitled under the Newgard Agreement and the Kouhdari Agreement, respectively.

Transitional Employment Agreements with Glacier Bank

Glacier Bank has entered into transitional employment agreements with Messrs. Newgard and Kouhdari (the “Transitional Employment Agreements”). The Transitional Employment Agreements are effective on (and conditioned upon) the closing of the merger. Each Transitional Employment Agreement provides for the executive to serve as an employee of Glacier Bank following the closing of the merger until 60 days after the Bank’s core system conversion (the final day of such period, the “Retention Date”). During such period, the executive will be paid for continuing services based on his annualized base salary as provided in the applicable Transitional Employment Agreement. Under each Transitional Employment Agreement, effective on the Retention Date, unless the parties otherwise agree, the executive’s position will be eliminated.

The Transitional Employment Agreements provide that (1) Mr. Newgard will be entitled to receive lump-sum cash payments of (i) $250,000, payable following the Bank’s core system conversion; and (ii) $200,000, payable after the Retention Date, in each case provided that Mr. Newgard has remained continuously employed through such date, as well as a prorated bonus of up to 20% of his base salary payable in accordance with Glacier’s existing short term incentive plan; and (2) Mr. Kouhdari is eligible to receive a prorated discretionary bonus of up to 40% of his base salary.

For each of Messrs. Newgard and Kouhdari, if Glacier Bank terminates the executive’s employment during the “Term” without “Cause” or the executive terminates his employment during the Term for “Good Reason” (as such terms are defined in the applicable Transitional Employment Agreement), the executive’s right to receive the payments described above (excluding the right to receive any discretionary bonus) will remain in effect.

ESOP and 401(k) Plan Accelerated Vesting

Executive officers of BOID and the Bank are participants in the ESOP and/or the 401(k) Plan. The ESOP and the 401(k) Plan are being terminated in conjunction with the closing of the merger and, as a result, the accounts of participants in the ESOP and the 401(k) Plan, to the extent they are not already vested, shall fully vest and be 100 percent non-forfeitable, and the ESOP and the 401(k) Plan shall permit the entire balance of a

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participant’s account to be distributable following receipt of a determination by the Internal Revenue Service that termination of the ESOP and the 401(k) Plan does not adversely affect the ESOP’s or the 401(k) Plan’s tax-qualified status.

Prorated Portion of Target Annual Cash Incentive

Messrs. Newgard and Kouhdari and certain other members of BOID’s and the Bank’s executive management participate in the Bank’s annual cash incentive plan (the “Annual Plan”). In connection with the closing of the Merger, each of these individuals will receive a prorated portion of the bonus he or she would have been entitled to receive under the Annual Plan based on BOID’s projected performance through the remainder of the year. For example, if the merger closed on June 30, 2025 and an executive would have been entitled to a bonus equal to 40% of his salary as of December 31, 2025, the executive would receive a bonus equal to 20% of his salary in connection with closing.

Accelerated Vesting of Restricted Stock, RSUs, Options and SARs, as applicable

The directors and certain executive officers of BOID have previously received BOID restricted stock, RSUs, Options and/or SARs that vest over time. All outstanding BOID Options and SARs that remain unexercised will be automatically canceled at the effective time of the merger and, regardless of whether the BOID Options or SARs had become vested and exercisable before the effective time of the merger, the holders of the outstanding BOID Options and SARs will be paid in cash an amount per share equal to the spread, if any, between (a) the product of the Glacier average closing price (as defined in the merger agreement) multiplied by the per share stock consideration and (b) the exercise price per share of such BOID Option or SAR, net of any cash that must be withheld under applicable tax laws. Any BOID Option or SAR that has an exercise price per share that is equal to or greater than the amount described in (a) above will be cancelled without any payment. Immediately prior to the closing of the merger, each outstanding share of restricted stock or RSU will vest, the RSUs will be settled in BOID common shares, and each resulting BOID common share will be entitled to receive the per share stock consideration and cash in lieu of fractional shares.

Stock Ownership

As described below under “Information Concerning Bank of Idaho Holding Co.—Share Ownership of Principal Shareholders, Management and Directors of BOID” and “The Merger —Merger Consideration”, as of the record date, BOID directors, executive officers and their related entities beneficially owned [   ] BOID common shares. BOID directors and executive officers will receive the same consideration in the merger for their shares as will other BOID shareholders.

Indemnification of Directors and Officers; Insurance

The merger agreement provides that Glacier will, for a period of six years following the closing of the merger, indemnify the present and former directors and officers of BOID and the Bank against liabilities or costs that may arise in the future, incurred in connection with claims or actions arising out of or pertaining to matters that existed or occurred prior to the effective date of the merger. The scope of this indemnification will be to the fullest extent that such persons would have been entitled to indemnification under applicable law, BOID’s Articles of Incorporation or the Bank’s Articles of Incorporation or BOID’s bylaws or the Bank’s bylaws, as applicable.

The merger agreement also provides that Glacier will purchase, at the sole cost and expense of BOID and with BOID’s cooperation, a six-year “tail” policy for BOID’s current directors’ and officers’ liability insurance with respect to claims arising from facts or events that occurred before the effective date of the merger, provided that the premiums for such policy shall not exceed 200 percent of the current annualized premiums.

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Interests of Directors Combined

In conjunction with the merger agreement, members of the BOID Board executed voting agreements to vote their respective share holdings in support of the merger and also executed non-competition, non-solicitation, and confidentiality agreements as described below. As of the closing date of the merger, members of the BOID Board and the board of directors of the Bank will resign from those boards.

Glacier Directors and Executive Officers

Each of the directors and executive officers of Glacier prior to the merger will remain the directors and officers of Glacier following the completion of the merger.

Additional Agreements

Voting Agreements

As described above under “—Voting Agreements,” each of the directors, executive officers and certain significant shareholders of BOID have entered into a voting agreement, dated as of January 13, 2025. Pursuant to the voting agreement, each signing person agrees to vote the BOID common shares that they are entitled to vote and that they own or control in favor of approval of the merger agreement.

Non-Competition, Non-Solicitation, and Confidentiality Agreement

The directors of BOID and the Bank (each, a “Director”) have entered into a Non-Competition, Non-Solicitation, and Confidentiality Agreement with Glacier, Glacier Bank, BOID, and the Bank, dated January 13, 2025 (the “Non-Competition Agreement”). The Non-Competition Agreement establishes certain obligations of each Director not to compete with Glacier or Glacier Bank for a specified amount of time following the merger. Except under certain limited circumstances, the Non-Competition Agreement prohibits each Director from becoming involved in any depository, financial, or lending institution, wealth management company, or trust company, or any holding thereof, which operates within a certain geographic area. The Non-Competition Agreement also generally prohibits each Director from soliciting Glacier’s or Glacier Bank’s employees, customers, business partners, or joint venturers. For each Director, the term of the Non-Competition Agreement commences upon the effective date of the merger and continues until the later to occur of (i) two (2) years after the effective date of the merger, or (ii) if applicable, one (1) year after the termination of any service by such Director as a post-merger member of an advisory board for a division of Glacier Bank. A carve-out from certain provisions of the Non-Competition Agreement has been made for two Directors of the Bank due to special circumstances relating to their respective roles as representatives of institutional shareholders of BOID that are active investors in other banks. Nothing in the Non-Competition Agreement prevents a Director from becoming involved with a financial institution that has no material operations in the covered geographic area, and it further provides that a Director may request in advance and in writing that Glacier waive the restrictions set forth in the Non-Competition Agreement with respect to a particular proposed activity with a competing business.

Regulatory Requirements

Closing of the merger is subject to approval or waiver by the appropriate banking regulatory authorities, including the Federal Deposit Insurance Corporation, the Board of Governors of the Federal Reserve System, the Commissioner of the Montana Division of Banking and Financial Institutions, and the Idaho Department of Finance. The U.S. Department of Justice is able to provide input during this approval process as appropriate to analyze, and in some cases challenge, the merger on antitrust grounds. Glacier and BOID have filed or will file all required applications and waiver requests to obtain the regulatory approvals and waivers or non-objections necessary to consummate the merger. Glacier and BOID cannot predict whether the required regulatory approvals and waivers or non-objections will be obtained, when they will be received or whether they will be subject to any conditions.

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Material U.S. Federal Income Tax Consequences of the Merger to BOID Shareholders

This section generally describes the anticipated material U.S. federal income tax consequences of the merger of BOID with and into Glacier, to U.S. holders (as defined below) of BOID common shares who exchange BOID common shares for shares of Glacier common stock pursuant to the merger. The summary is based on the Internal Revenue Code, applicable Treasury Regulations, judicial decisions and administrative rulings and decisions, all as in effect as of the date hereof, and all of which are subject to change, possibly with retroactive effect. The summary does not address any tax consequences of the merger under state, local or foreign laws, or any federal laws other than those pertaining to income tax.

For purposes of this discussion, a “U.S. holder” is a beneficial owner of BOID common shares who for U.S. federal income tax purposes is:

If a partnership (including for this purpose any entity treated as a partnership for U.S. federal income tax purposes) holds BOID common shares, the tax treatment of a partner generally will depend on the status of the partner and the activities of the partnership. If you are a partnership holding BOID common shares, or a partner therein, you should consult your tax advisor about the consequences of the merger to you.

This discussion addresses only those BOID shareholders that hold their BOID common shares as a capital asset within the meaning of Section 1221 of the Internal Revenue Code (generally, property held for investment), and does not address all the U.S. federal income tax consequences that may be relevant to particular BOID shareholders in light of their individual circumstances or to BOID shareholders that are subject to special rules, including, without limitation:

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In addition, the discussion does not address any alternative minimum tax or any state, local or non-U.S. tax consequences of the merger, nor does it address the 3.8% U.S. Medicare contribution surtax.

It is a condition to the respective obligations of Glacier and BOID to complete the merger that each party will have obtained from its counsel an opinion to the effect that the merger will for U.S. federal income tax purposes qualify as a “reorganization” within the meaning of Section 368(a) of the Internal Revenue Code. The opinions will assume that the merger will be completed according to the terms of the merger agreement and that the parties will report the transaction in a manner consistent with the opinion. The opinions will rely on the facts as stated in the merger agreement, the Registration Statement on Form S-4 (of which this proxy statement/prospectus is a part) and certain other documents. The opinions will be based on facts and representations contained in representation letters provided by Glacier and BOID to be delivered at the time of closing and based on customary factual assumptions. If any fact, assumption or representation upon which either such opinion is based is or becomes inaccurate, the accuracy of such opinion and the U.S. federal income tax consequences of the merger could be adversely affected. The opinions will be based on statutory, regulatory and judicial authority existing as of the date of the opinion, any of which may be changed at any time with retroactive effect. An opinion of counsel represents such counsel’s best legal judgement, but the opinion is not binding on the Internal Revenue Service or the courts. Neither Glacier nor BOID has requested and neither intends to request any ruling from the Internal Revenue Service as to the U.S. federal income tax consequences of the merger. Consequently, no assurance can be given that the Internal Revenue Service will not assert, or that a court will not sustain, a position contrary to any of the tax consequences described below or any of the tax consequences described in the opinions. Accordingly, each BOID shareholder should consult their tax advisor with respect to the particular tax consequences of the merger to such holder.

The following discussion generally assumes that the merger qualifies as a “reorganization” within the meaning of Section 368(a) of the Internal Revenue Code.

Tax Consequences of the Merger Generally to Holders of BOID Common Shares. If the merger of BOID with and into Glacier is a reorganization within the meaning of Section 368(a) of the Internal Revenue Code, the tax consequences of the merger to U.S. holders of BOID common shares will be as follows (except with respect to any cash received instead of fractional share interests in Glacier common stock, as discussed in the section entitled “Cash Received Instead of a Fractional Share of Glacier Common Stock”):

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If a U.S. holder of BOID common shares acquired different blocks of BOID common shares at different times or at different prices, any gain or loss will be determined separately with respect to each block of BOID common shares and such holder’s basis and holding period in their shares of Glacier common stock may be determined with reference to each block of BOID common shares. Any such holders should consult their tax advisors regarding the manner in which Glacier common stock received in the exchange should be allocated among different blocks of BOID common shares and with respect to identifying the bases or holding periods of the particular shares of Glacier common stock received in the merger.

Gain that a U.S. holder of BOID common shares recognizes in connection with the merger generally will constitute capital gain, except to the extent recharacterized as dividend income, and will constitute long-term capital gain if such holder has held (or is treated as having held) their BOID common shares for more than one year as of the date of the merger. Long-term capital gain of non-corporate holders of BOID common shares is generally taxed at preferential rates. In some cases, including with respect to certain U.S. holders that actually or constructively own Glacier stock other than Glacier stock received pursuant to the merger, the recognized gain could be treated as having the effect of a distribution of a dividend under the tests set forth in Section 302 of the Internal Revenue Code, in which case such gain would be treated as dividend income. A dividend from Glacier could be treated as a “qualified dividend” and, as such, taxed at the same rates applicable to long-term capital gains so long as the requisite holding period is met. Because the possibility of dividend treatment depends primarily upon each holder’s particular circumstances, including the application of certain constructive ownership rules, holders of BOID common shares should consult their tax advisors regarding the application of the foregoing rules to their particular circumstances and the potential treatment of gain with respect to the merger as dividend income.

Cash Received Instead of a Fractional Share of Glacier Common Stock. A holder of BOID common shares who receives cash instead of a fractional share of Glacier common stock will generally be treated as having received the fractional share pursuant to the merger and then as having that fractional share of Glacier common stock redeemed for cash. The deemed redemption will generally be treated as a sale or exchange and, as a result, a holder of BOID common shares will generally recognize gain or loss equal to the difference between the amount of cash received in lieu of the fractional share and the basis in their fractional share interest as set forth above. Except to the extent of any amounts recharacterized as dividend income as described above, this gain or loss will generally be capital gain or loss, and will be long-term capital gain or loss if, as of the effective date of the merger, the holding period for such shares is greater than one year. The deductibility of capital losses is subject to limitations.

Payment of Special Distribution. Under the merger agreement, if BOID’s capital prior to the closing of the merger is in excess of a specified minimum amount, BOID may in its discretion declare and pay a special distribution in the amount of such excess to holders of its common stock as of the record date for the special distribution, without regard to whether such holders continue to hold any BOID common shares through the closing of the merger and surrender their BOID common shares and receive shares of Glacier common stock in exchange therefor. While the issue is not free from doubt, BOID intends to treat that special distribution as a distribution in respect of BOID common shares, rather than as cash consideration paid to BOID shareholders in connection with the merger. Nonetheless, there is a risk that the Internal Revenue Service could take a contrary position, and that the courts could affirm such a contrary position, and BOID cannot assure shareholders that its intended treatment will be upheld.

If, in accordance with BOID’s intended treatment, the special distribution is treated as a separate distribution with respect to BOID common shares, it will be treated as a dividend to the extent of BOID’s current or accumulated earnings and profits as determined for U.S. federal income tax purposes, and as described above could be treated as a “qualified dividend.” Any remaining amount of such distribution in excess of BOID’s current and accumulated earnings and profits would be treated as a return of capital to the extent of a U.S. holder’s basis in its BOID common shares and thereafter as capital gain. Any such capital gain would constitute long-term capital gain if such U.S. holder has held (or is treated as having held) its BOID common shares for

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more than one year as of the date of the distribution. Long-term capital gain of non-corporate taxpayers, including individuals, is generally taxed at preferential rates. By contrast, if BOID’s intended treatment is not upheld and the special distribution is integrated with the merger, the special distribution will be treated as cash received by BOID shareholders in the merger and will be subject to the analysis described above in the section entitled “Tax Consequences of the Merger Generally to Holders of BOID Common Shares.”

Backup Withholding and Information Reporting. In general, information reporting requirements may apply to cash payments, if any, made to a holder of BOID common shares in connection with the merger, unless an exemption applies. Payments of cash made to a holder of BOID common shares may, under certain circumstances, be subject to backup withholding at a current rate of 24%, unless the holder provides proof of an applicable exemption satisfactory to Glacier and the exchange agent or furnishes its taxpayer identification number, and otherwise complies with all applicable requirements of the backup withholding rules. Any amounts withheld from cash payments made to a holder of BOID common shares under the backup withholding rules are not additional tax and will be allowed as a refund or credit against the holder’s U.S. federal income tax liability, if any, provided the required information is furnished to the Internal Revenue Service.

The preceding discussion is intended only as a summary of the material U.S. federal income tax consequences of the merger to U.S, holders of BOID common shares. It is not a complete analysis or discussion of all potential tax effects that may be important to you. Thus, you are strongly encouraged to consult your tax advisor as to the specific tax consequences resulting from the merger, including tax return reporting requirements, the applicability and effect of U.S. federal, state, local, and other tax laws and the effect of any proposed changes in the tax laws.

Accounting Treatment of the Merger

The acquisition of BOID will be accounted for using the acquisition method of accounting by Glacier under GAAP. Accordingly, using the acquisition method of accounting, the assets and liabilities of BOID will be recorded by Glacier at their respective fair values at the time of the merger. The excess of Glacier’s purchase price over the net fair value of assets acquired including identifiable intangible assets and liabilities assumed will be recorded as goodwill. Goodwill will be periodically assessed for impairment but no less frequently than on an annual basis. Prior period financial statements are not restated and results of operation of BOID will be included in Glacier’s consolidated statement of operations after the date of the merger. The identifiable intangible assets with finite lives, other than goodwill, will be amortized against the combined company’s earnings following completion of the merger. The fair value adjustments will be recognized in the consolidated statement of operations after the date of the merger over the estimated lives of the respective assets and liabilities.

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INFORMATION CONCERNING GLACIER

Glacier Bancorp

49 Commons Loop

Kalispell, Montana 59901

Telephone: (406) 756-4200

Glacier is a Montana corporation and a registered bank holding company under the BHC Act. It was incorporated in 2004 as a successor corporation to the Delaware corporation originally incorporated in 1990 and is the bank holding company of Glacier Bank. Glacier Bank is a Montana state-chartered bank, which commenced operations in 1991 and is regulated primarily by the Montana Division of Banking and Financial Institutions and the Federal Deposit Insurance Corporation. Glacier Bank has 227 locations, consisting of 194 branches and 33 loan or administration offices, in 85 counties within 8 states including Montana, Idaho, Utah, Washington, Wyoming, Colorado, Arizona and Nevada.

Glacier Bank offers a wide range of banking products and services, including: retail banking; business banking; real estate, commercial, agriculture and consumer loans; and mortgage origination and loan servicing. Glacier Bank serves individuals, small to medium-sized businesses, community organizations and public entities.

As of December 31, 2024, Glacier had total assets of approximately $27.9 billion, total net loans receivable of approximately $17.1 billion, total deposits of approximately $20.5 billion and approximately $3.2 billion in shareholders’ equity.

Glacier common stock is traded on The New York Stock Exchange under the ticker symbol “GBCI”.

Additional information about Glacier and Glacier Bank may be found in the documents incorporated by reference into this proxy statement/prospectus. Please see the section entitled “Where You Can Find More Information.”

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INFORMATION CONCERNING BANK OF IDAHO HOLDING CO.

General

BOID is an Idaho corporation and a registered bank holding company under the BHC Act. It was incorporated in 1999 and is the bank holding company of the Bank. BOID has no substantial operations separate or apart from the Bank. The Bank is an Idaho state-chartered bank which commenced operations in 1985 and is regulated by the Idaho Department of Finance and the Federal Deposit Insurance Corporation.

The Bank’s principal office is located in Idaho Falls, Idaho and the Bank maintains branch offices in Bonneville, Fremont, Bannock, Ada, and Canyon Counties in Idaho and in Franklin, Columbia, Yakima, and Benton Counties in Washington.

As of December 31, 2024, BOID had total assets of approximately $1.3 billion, total net loans receivable of approximately $1.0 billion, total deposits of approximately $1.1 billion and approximately $131.4 million in shareholders’ equity.

Market Area

BOID’s principal market area consists of Idaho and eastern Washington.

Lending Activities

The Bank’s principal business is to accept deposits from the public and to make loans and other investments. For businesses, the Bank provides commercial real estate term loans, agricultural real estate loans, commercial and industrial term loans, lines of credit, loans for working capital, loans for business expansion and the purchase of equipment and machinery, and construction and land development loans for builders and developers. The Bank also offers a variety of traditional loan products to its consumer customers which are primarily mortgage loans, home equity loans, automobile loans and various other consumer installment loans.

At December 31, 2024, the Bank’s total gross loan portfolio of approximately $1.03 billion represented approximately 78% of the Bank’s total assets. As of such date, the Bank’s loan portfolio primarily consisted of 42% commercial real estate secured loans (excluding construction and land development loans), 4% farmland loans, 5% agricultural production, 13% one- to four-family residential real estate secured loans, 15% real estate construction and land development loans, 6% multi-family loans, 14% commercial loans, and 1% consumer and other loans.

Deposit and Banking Services

Customers of the Bank receive a full suite of traditional banking and deposit products. The Bank engages in most of the business operations customarily conducted by independent financial institutions in Idaho, including the acceptance of checking accounts, savings accounts, money market accounts and a variety of certificates of deposit accounts.

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The Bank conducts a substantial amount of business with individuals, as well as with small to medium-sized businesses. The primary sources of core deposits are residents of the Bank’s primary market area and businesses and their employees located in that area. The Bank also obtains deposits through local advertising. For the convenience of its customers, the Bank offers drive-through banking facilities, Internet and telephone banking, check/ATM cards, direct deposit, night depositories, personalized checks, and merchant services. The Bank’s services also include cashier’s checks, domestic wire transfers, account research, stop payments, and telephone and Internet-based transfers between accounts.

BOID Summary Financial Information

The following selected financial information is derived from financial statements of BOID.

Competition

BOID experiences competition in both lending and attracting funds from other commercial banks, savings banks, savings and loan associations, credit unions, finance companies, pension trusts, mutual funds, insurance companies, mortgage bankers and brokers, brokerage and investment banking firms, asset-based non-bank lenders, government agencies, financial technology companies and certain other non-financial institutions, which may offer more favorable financing alternatives than BOID. BOID also competes with companies located outside

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of its primary market that provide financial services to persons within its primary market. Some of BOID’s current and potential competitors have larger customer bases, greater brand recognition, and significantly greater financial, marketing and other resources than BOID and some of them are not subject to the same degree of regulation as BOID.

Employees

As of December 31, 2024, BOID and the Bank had 191 full-time and 5 part-time employees. BOID believes that it has a good working relationship with its employees and the employees are not represented by a collective bargaining agreement.

Properties

BOID’s principal office is located in Idaho Falls, Idaho. In addition to its principal office, BOID operates, through the Bank, branch offices in Bonneville, Fremont, Bannock, Ada, and Canyon Counties in Idaho and in Franklin, Columbia, Yakima, and Benton Counties in Washington. All properties and buildings are owned with the exception of ten locations, which occupy leased properties. The terms of these leases range from one to fifteen years with expiration dates ranging from 2025 to 2032 and renewal options ranging from one to five years.

Legal Proceedings

From time to time, litigation arises in the normal conduct of BOID’s business. BOID, however, is not currently involved in any litigation that management of BOID believes, either individually or in the aggregate, could reasonably be expected to have a material adverse effect on its business, financial condition or results of operations.

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Share Ownership of Principal Shareholders, Management and Directors of BOID

The following table shows, as of December 31, 2024, the beneficial ownership of BOID common stock by (i) each person known by BOID to be the beneficial owner of more than 5% of BOID’s outstanding common stock, (ii) each of BOID’s directors and executive officers; and (iii) all of BOID’s directors and officers as a group. Except as otherwise noted in the footnotes to the table, each individual has sole investment and voting power with respect to the shares of common stock set forth.

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DESCRIPTION OF GLACIER’S CAPITAL STOCK

Glacier’s authorized capital stock consists of 234,000,000 shares of common stock, $0.01 par value per share, and 1,000,000 shares of preferred stock, $0.01 par value per share. As of the date of this proxy statement/prospectus, Glacier had no shares of preferred stock issued. The Glacier Board is authorized, without further shareholder action, to issue shares of preferred stock with such designations, preferences and rights as the Glacier Board may determine.

Glacier common stock is listed for trading on The New York Stock Exchange under the symbol “GBCI.”

Glacier’s shareholders do not have preemptive rights to subscribe to any additional securities that may be issued. Each share of Glacier common stock has the same relative rights and is identical in all respects to every other share of Glacier common stock. If Glacier is liquidated, the holders of Glacier common stock are entitled to share, on a pro rata basis, Glacier’s remaining assets after provision for liabilities.

For additional information concerning Glacier’s capital stock, see “Comparison of Certain Rights of Holders of Glacier and BOID Common Shares” below.

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COMPARISON OF CERTAIN RIGHTS OF HOLDERS OF

GLACIER AND BOID COMMON SHARES

Montana law, Glacier’s articles and Glacier’s bylaws govern the rights of Glacier’s shareholders and will govern the rights of BOID’s shareholders, who will become shareholders of Glacier as a result of the merger. The rights of BOID’s shareholders are currently governed by Idaho law, BOID’s Articles of Incorporation and BOID’s bylaws. The following is a brief summary of certain differences between the rights of Glacier and BOID shareholders. This summary is not intended to provide a comprehensive discussion of each company’s governing documents. This summary is qualified by the documents referenced and the laws of Montana and Idaho. See also “Where You Can Find More Information.”

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CERTAIN LEGAL MATTERS

Miller Nash and Otteson Shapiro will deliver at the effective time of the merger their opinions to Glacier and BOID as to certain United States federal income tax consequences of the merger. Please see the section entitled “Material U.S. Federal Income Tax Consequences of the Merger to BOID Shareholders” beginning on page 52. The validity of the Glacier common stock to be issued in the merger will be passed upon for Glacier by its special counsel, Moore, Cockrell, Goicoechea & Johnson, P.C., Kalispell, Montana.

EXPERTS

The consolidated financial statements of Glacier as of December 31, 2024 and 2023 and for each of the years in the three-year period ended December 31, 2024 have been incorporated by reference herein and in the registration statement in reliance upon the reports of Forvis Mazars, LLP, independent registered public accounting firm, and upon the authority of said firm as experts in accounting and auditing.

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WHERE YOU CAN FIND MORE INFORMATION

The SEC allows Glacier to “incorporate by reference” information into this proxy statement/prospectus, which means that Glacier can disclose important information to you by referring you to another document filed separately by Glacier with the SEC. The information incorporated by reference is deemed to be part of this proxy statement/prospectus, except for any information superseded by any information in this proxy statement/prospectus.

This proxy statement/prospectus incorporates by reference the documents set forth below that Glacier has previously filed with the SEC. These documents contain important information about Glacier and its finances:

In addition, Glacier is incorporating by reference additional documents that Glacier files with the SEC under Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act between the date of this proxy statement/prospectus and the date of the BOID special meeting, provided, however, that Glacier is not incorporating by reference any information furnished (but not filed), except as otherwise specified therein.

Glacier files annual, quarterly and special reports, proxy statements and other business and financial information with the SEC. You may obtain the information incorporated by reference and any other materials Glacier may file with the SEC without charge by following the instructions in the section entitled “References to Additional Information” in the forepart of this document.

BOID

BOID does not have a class of securities registered under Section 12 of the Exchange Act, is not subject to the reporting requirements of Section 13(a) or 15(d) of the Exchange Act, and accordingly does not file documents or reports with the SEC.

If you have questions concerning the merger or this proxy statement/prospectus, would like additional copies of this proxy statement/prospectus, would like copies of BOID’s Articles of Incorporation or bylaws, or would like copies of BOID’s historical consolidated financial statements or need help voting your shares, please contact:

Bank of Idaho Holding Co.

350 Memorial Drive

Idaho Falls, Idaho 83402

ATTN: Shanon Taylor, Corporate Secretary

(888) 396-5757

You should rely only on the information contained or incorporated by reference in this proxy statement/prospectus in deciding how to vote on the merger. We have not authorized anyone to provide you with information other than what is contained in this proxy statement/prospectus. This proxy statement/prospectus is dated [   ], 2025. You should not assume that information contained in this proxy statement/prospectus is accurate as of any other date, and neither the mailing of this proxy statement/prospectus to BOID shareholders nor the issuance of Glacier common stock in the merger will create any implication to the contrary.

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Appendix A

EXECUTION VERSION

PROJECT HUCKLEBERRY

PLAN AND AGREEMENT OF MERGER

AMONG

GLACIER BANCORP, INC.

GLACIER BANK

BANK OF IDAHO HOLDING CO. AND

BANK OF IDAHO

DATED AS OF JANUARY 13, 2025

A-i

A-ii

PLAN AND AGREEMENT OF MERGER

AMONG

GLACIER BANCORP, INC., GLACIER BANK,

BANK OF IDAHO HOLDING CO. AND BANK OF IDAHO

This Plan and Agreement of Merger (the “Agreement”), dated as of January 13, 2025, is made by and among GLACIER BANCORP, INC. (“GBCI”), GLACIER BANK (“Glacier Bank”), BANK OF IDAHO HOLDING CO. (“BOID”), and BANK OF IDAHO (the “Bank”).

PREAMBLE

The boards of directors of GBCI and BOID believe that the proposed Merger (as defined below), to be accomplished in the manner set forth in this Agreement, is in the best interests of the respective corporations and their shareholders.

Capitalized terms used in this Agreement but not immediately defined are used with the meanings given under the heading “Definitions” below.

RECITALS

A. The Parties.

(1) GBCI is a corporation duly organized and validly existing under the laws of the State of Montana and is a registered bank holding company under the Bank Holding Company Act of 1956, as amended (“BHC Act”). GBCI’s principal office is located in Kalispell, Montana.

(2) Glacier Bank is a duly organized and validly existing Montana state-chartered bank and a wholly owned subsidiary of GBCI. Glacier Bank maintains its principal office in Kalispell, Montana, and currently operates 17 separately-branded banking divisions.

(3) BOID is a corporation duly organized and validly existing under the laws of the State of Idaho and is a registered bank holding company under the BHC Act. BOID’s principal office is located in Idaho Falls, Idaho.

(4) The Bank is an Idaho state-chartered commercial bank, duly organized and validly existing under the laws of the State of Idaho and a wholly owned subsidiary of BOID. The Bank’s principal office is located in Idaho Falls, Idaho. Including its principal office, the Bank maintains a total of 15 branch offices in Bonneville, Fremont, Bannock, Ada, and Canyon Counties in Idaho and in Franklin, Columbia, Spokane, Yakima, and Benton Counties in Washington.

B. The Transactions. On the Effective Date, BOID will merge with and into GBCI, with GBCI as the surviving entity (the “Merger”), and immediately thereafter and on the same day, the Bank will merge with and into Glacier Bank, with Glacier Bank surviving as a wholly owned subsidiary of GBCI (the “Bank Merger,” and with the Merger, the “Transactions”). Following completion of the Transactions, the former branches of the Bank will be integrated with Glacier Bank’s existing divisions operating in Idaho and Washington.

C. Board Approvals. The respective boards of directors of GBCI and Glacier Bank have adopted and approved this Agreement and authorized its execution and delivery, the respective boards of directors of BOID and the Bank have adopted this Agreement and authorized its execution and delivery, and the board of directors of BOID has directed that this Agreement be submitted to holders of BOID Common Stock for approval and unanimously recommended that such BOID shareholders vote in favor of approval of this Agreement and the Merger.

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D. Other Conditions. The Transactions are subject to: (1) satisfaction of the conditions described in this Agreement; (2) approval of this Agreement and/or the Merger by holders of BOID Common Stock; and (3) approval of, or granting of a waiver applicable to, the Transactions by the FDIC and the Federal Reserve (as applicable), the Montana Commissioner, the Idaho Department of Finance, and any other agencies having jurisdiction over the Transactions.

E. Director and Voting Agreements. In connection with the parties’ execution of this Agreement, (1) the directors and executive officers of BOID, and the holders or groups holding outstanding shares of BOID Common Stock that are identified on Exhibit A, have entered into agreements pursuant to which, among other things, such persons agreed to vote all BOID Common Stock beneficially owned by such persons in favor of approving this Agreement and the transactions contemplated by this Agreement, and (2) the directors of BOID and the Bank have entered into agreements pursuant to which, among other things, such directors agreed, following the Closing of the Transactions, to refrain from competing with GBCI and/or Glacier Bank or soliciting its customers or employees for a period of time specified in such agreements.

F. Intention of the Parties—Tax Treatment. The parties intend that the Merger shall qualify, for federal income tax purposes, as a reorganization under IRC Section 368(a), and that this Agreement shall constitute the “plan of reorganization” of the Merger for purposes of IRC Section 368.

AGREEMENT

In consideration of the mutual agreements set forth in this Agreement, GBCI, Glacier Bank, BOID and the Bank agree as follows:

DEFINITIONS

The following capitalized terms used in this Agreement will have the following meanings:

“ACL” means the allowance for credit losses, as applicable.

“Acquisition Event” means any of the following: (a) a merger, consolidation, share exchange, or similar transaction involving BOID, the Bank, or any successor, (b) a purchase or other acquisition in one or a series of related transactions of assets of BOID or any BOID Subsidiaries representing 30 percent or more of the consolidated assets of BOID and its Subsidiaries, or 30 percent or more of any class of equity or voting securities of BOID or any BOID Subsidiaries whose assets constitute 30 percent or more of the consolidated assets of BOID and its Subsidiaries, or (c) a purchase or other acquisition (including by way of tender offer, exchange offer, or any similar transaction) that if consummated, would result in an acquisition in one or a series of related transactions of beneficial ownership of securities representing 50 percent or more of the voting power of BOID or its Subsidiaries, in each case with or by a Person or entity other than GBCI or one of its Subsidiaries.

“Acquisition Proposal” has the meaning assigned to such term in Section 4.1.9.

“Affiliates” has the meaning set forth in Rule 12b-2 of the Exchange Act.

“Agreement” means this Plan and Agreement of Merger.

“Anticipated Closing Date” has the meaning set forth in Section 4.12.

“Appraisal Laws” means Sections 30-29-1301 through 30-29-1340 of the Idaho Statutes, as such sections may be applicable to a merger in which the corporation to be merged out of existence is organized under the laws of the State of Idaho.

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“Articles of Merger” has the meaning assigned to such term in Section 2.1.

“Asset Classification” has the meaning assigned to such term in Section 3.1.14(a).

“Bank” has the meaning assigned to it in the first paragraph, as supplemented by the first sentence of Recital A(4).

“Bank Financial Statements” means the Bank’s (a) unaudited balance sheets as of December 31, 2021, 2022, and 2023, and the related statements of income, cash flows and changes in shareholder’s equity for each of the years then ended, and (b) unaudited balance sheets as of September 30, 2024, and the related unaudited statement of income, together with the Subsequent Bank Financial Statements.

“Bank Merger” has the meaning assigned to such term in Recital B.

“Bank Merger Agreement” means the bank merger agreement by and between Glacier Bank and the Bank to be entered into concurrently with this Agreement pursuant to which the Bank Merger will be effected.

“BHC Act” has the meaning assigned to such term in Recital A(1).

“BOID” has the meaning assigned to it in the first paragraph, as supplemented by the first sentence of Recital A(3).

“BOID 401(k)” means the Bank of Idaho 401(k) Plan.

“BOID Capital” means BOID’s capital stock, surplus and retained earnings determined in accordance with GAAP on a consolidated basis, net of goodwill and other intangible assets, calculated in the same manner in which BOID’s consolidated tangible equity capital at September 30, 2024, was determined, after giving effect to adjustments, calculated in accordance with GAAP, for accumulated other comprehensive income or loss as reported on BOID’s or the Bank’s balance sheet. BOID Closing Capital will also reflect the accumulated income or loss related to the fair value of BOID’s held-to-maturity securities as calculated in the same manner as the accumulated other comprehensive income or loss shown on the Bank’s balance sheet for available-for-sale securities. For purposes of determining BOID Closing Capital, purchase accounting adjustments and the Final Transaction Related Expenses of up to the Maximum Transaction Expense Amount will not be taken into account. To the extent Final Transaction Related Expenses exceed the Maximum Transaction Expense Amount, the difference, on an after-tax basis (applying an effective tax rate of 21.0 percent to reflect proportionately items that are deductible under applicable Tax Laws to those that are not), will be treated as a reduction of BOID Capital for purposes of determining BOID Closing Capital to the extent such amounts have not, as of the date of determination, been accrued or paid by BOID or the Bank (regardless of whether such amounts are required to be expensed in accordance with GAAP). If Final Transaction Related Expenses are less than the Maximum Transaction Expense Amount, the difference, on an after-tax basis (applying an effective tax rate of 21.0 percent to the extent a particular item is deductible under applicable Tax Laws), will be treated as an increase in BOID Capital for such purpose; except as otherwise described in Schedule 1 to Exhibit B.

“BOID Class B Stock” means BOID non-voting Class B common stock, no par value, issued and outstanding from time to time.

“BOID Closing Capital” has the meaning assigned to such term in Section 4.12.

“BOID Common Stock” means BOID voting common stock, no par value, issued and outstanding from time to time.

“BOID ESOP” means the Bank of Idaho Holding Company Employee Stock Ownership Plan.

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“BOID Financial Statements” means BOID’s (a) audited consolidated balance sheets as of December 31, 2021, 2022, and 2023, and the related statements of income, cash flows and changes in shareholders’ equity for each of the years then ended, and (b) unaudited consolidated balance sheet as of September 30, 2024, and the related unaudited consolidated statements of income, cash flows, and changes in shareholders’ equity for the period then ended.

“BOID Meeting” has the meaning assigned to such term in Section 4.2.2.

“BOID Options” has the meaning assigned to such term in Section 3.1.3(c).

“BOID Regulatory Reports” has the meaning assigned to such term in Section 3.1.4(a).

“BOID Reports” has the meaning assigned to such term in Section 3.1.4(c).

“BOID Restricted Stock” has the meaning assigned to such term in Section 1.4.4.

“BOID RSUs” has the meaning assigned to such term in Section 1.4.3.

“BOID SARs” has the meaning assigned to such term in Section 1.4.2.

“BOID Securities” has the meaning assigned to such term in Section 3.1.3(c).

“BOID Stock” means the shares of BOID Common Stock and BOID Class B Stock.

“BOID Stock Plans” means BOID’s 2019 Equity Incentive Plan and Second Amended and Restated 2006 Stock Appreciation Rights Plan.

“BOID Subordinated Debt” means BOID’s 5.75% Fixed-to-Floating Rate Subordinated Notes due 2030 and 3.375% Fixed-to-Floating Rate Subordinated Notes due 2031.

“BOID Subsidiaries” has the meaning assigned to such term in Section 3.1.1(c).

“Break-Up Fee” has the meaning assigned to such term in Section 7.5.

“Business Day” means any day other than a Saturday, Sunday, legal holiday or a day on which banking institutions located in the State of Montana or the State of Idaho are required by Law to remain closed.

“Certificate” has the meaning assigned to such term in Section 1.6.1.

“Claim” has the meaning set forth in Section 8.5.

“Closing” means the closing of the Transactions contemplated by this Agreement, as more fully specified in Section 2.2.

“Closing Capital Differential” means any positive or negative differential between the BOID Closing Capital and the Closing Capital Requirement.

“Closing Capital Requirement” means $122,126,000, plus the amount of BOID Closing Capital attributable to the exercise of BOID Options after September 30, 2024, if any.

“Compensation Plans” has the meaning assigned to such term in Section 3.1.18(c).

“Condition Satisfaction” has the meaning assigned to such term in Section 2.2.

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“Coordinator” has the meaning assigned to such term in Section 4.6.1.

“Confidentiality Agreement” means that certain Non-Disclosure Agreement, dated as of February 15, 2024, by and between GBCI and BOID.

“Covid-19 Relief Acts” means the Coronavirus Aid, Relief and Economic Security Act, the Economic Aid to Hard-Hit Small Businesses, Nonprofits, and Venues Act and the American Rescue Plan Act of 2021.

“Daily Closing Price” for any Trading Day means the daily closing price per share of GBCI Common Stock on the New York Stock Exchange, as reported on the website www.nyse.com.

“Determination Date” means the tenth day immediately preceding the Effective Date.

“Disclosure Schedule” has the meaning assigned to such term in Section 3.1.

“Dissenting Shares” means the shares of BOID Stock held by those shareholders who have properly exercised their dissenters’ rights in accordance with the Appraisal Laws.

“Effective Date” means the date on which the Effective Time occurs.

“Effective Time” means the time the Merger becomes effective under the MBCA and IBCA in accordance with Section 2.1.

“Employees” has the meaning assigned to such term in Section 3.1.18(c).

“Environmental Laws” has the meaning assigned to such term in Section 3.1.6(a)(ii).

“ERISA” means the Employee Retirement Income Security Act of 1974, as amended, and the rules and regulations thereunder.

“ERISA Affiliate” means, with respect to any Person, any other entity that is considered one employer with such Person under Section 4001(b) of ERISA or IRC Section 414(t).

“Exchange Act” means the Securities Exchange Act of 1934, as amended, and the rules and regulations thereunder.

“Exchange Agent” means American Stock Transfer & Trust Company, LLC.

“Exchange Fund” has the meaning assigned to such term in Section 1.5.

“Execution Date” means the date of this Agreement.

“Executive Officers” means, (a) with respect to GBCI and/or Glacier Bank Randall M. Chesler, Ronald J. Copher, and Donald J. Chery, and (b) with respect to BOID and/or the Bank, Caleb Dimick, Brian Kouhdari, Daivd Moe, Jeff Newgard, and Shanon Taylor.

“Fairness Opinion” has the meaning assigned to such term in Section 3.1.20.

“FDIC” means the Federal Deposit Insurance Corporation.

“Federal Reserve” means the Board of Governors of the Federal Reserve System.

“Final Transaction Related Expenses” has the meaning assigned to such term in Section 4.13.

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“GAAP” means United States generally accepted accounting principles.

“GBCI” has the meaning assigned to it in the first paragraph, as supplemented by the first sentence of Recital A(1).

“GBCI Average Closing Price” means the average Daily Closing Price of GBCI Common Stock for the 20 Trading Days immediately preceding the Determination Date.

“GBCI Common Stock” means the shares of GBCI common stock, $0.01 par value per share, issued and outstanding from time to time.

“GBCI Contracts” has the meaning assigned to such term in Section 3.2.2(a).

“GBCI Financial Statements” means GBCI’s (a) audited consolidated balance sheets as of December 31, 2021, 2022, and 2023, and the related audited consolidated statements of income, cash flows, and changes in shareholders’ equity for each of the years then ended, and (b) unaudited consolidated balance sheets as of September 30, 2024, and the related unaudited consolidated statements of income, cash flows, and changes in shareholders’ equity for the period then ended.

“GBCI Preferred Stock” means the shares of GBCI preferred stock, $0.01 par value per share.

“GBCI Regulatory Reports” has the meaning assigned to such term in Section 3.2.4(a).

“GBCI SEC Reports” has the meaning assigned to such term in Section 3.2.4(b).

“GBCI Shares” means the shares of GBCI Common Stock to be issued to the holders of BOID Stock as the Total Merger Consideration.

“GBCI Stock Plan” means the Glacier Bancorp, Inc. 2015 Stock Incentive Plan.

“GBCI Subsidiaries” means each Subsidiary of GBCI, including any corporation, bank, savings association, limited liability company, limited partnership, limited liability partnership or other organization acquired as a Subsidiary of GBCI after the date hereof and held as a Subsidiary by GBCI at the Effective Time.

“General Enforceability Exceptions” has the meaning assigned to such term in Section 3.1.1(d).

“Glacier Bank” has the meaning assigned to it in the first paragraph, as supplemented by the first sentence of Recital A(2).

“Governmental Authority” means any federal, state, local or non-U.S. government or subdivision thereof or any other governmental, administrative, judicial, taxing, arbitral, legislative, executive, regulatory or self-regulatory authority, instrumentality, agency, commission or body.

“Hazardous Substances” has the meaning assigned to such term in Section 3.1.6(a)(iii).

“IBCA” means the Idaho Business Corporation Act, as amended.

“Indemnified Parties” has the meaning assigned to such term in Section 6.3.1.

“Independent Accountants” has the meaning assigned to such term in Section 4.12.

“IRC” means the Internal Revenue Code of 1986, as amended, and the rules and regulations thereunder.

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“Knowledge” or any similar knowledge qualification in this Agreement has the following meanings: (a) BOID will be deemed to have “Knowledge” of a particular fact or matter if any Executive Officer of BOID or the Bank has actual knowledge of such fact or matter or if any such Person would reasonably be expected to discover or otherwise become aware of such fact or matter in the course of making a reasonable inquiry into such areas of BOID’s and the Bank’s business that are under such individual’s general area of responsibility; and (b) GBCI will be deemed to have “Knowledge” of a particular fact or matter if any Executive Officer of GBCI or Glacier Bank has actual knowledge of such fact or matter or if any such Person would reasonably be expected to discover or otherwise become aware of such fact or matter in the course of making a reasonable inquiry into such areas of GBCI’s and Glacier Bank’s business that are under such individual’s general area of responsibility.

“Law” means any law, rule, ordinance or regulation of any Governmental Authority, as from time to time amended, modified or supplemented, including (in the case of statutes) by succession of comparable successor Laws and the related regulations thereunder; provided that, for purposes of any representations and warranties contained in this Agreement that are made as of a specific date or dates, references to any Law shall be deemed to refer to such Law, as amended, and the related regulations thereunder as of such date.

“Lease” or “Leases” means and refers to, as applicable, each and all leases, subleases, licenses, concessions, and other agreements (written or oral) under which BOID or any BOID Subsidiary holds any Leased Real Estate, including the right to all security deposits and other amounts and instruments deposited by or on behalf of BOID or any BOID Subsidiary thereunder.

“Leased Real Estate” means all leasehold or subleasehold estates and other rights to use or occupy any land, buildings, structures, improvements, fixtures, or other interest in real property, including approved and unopened branch offices, off-premises ATM locations and other facilities, held by BOID or any BOID Subsidiary.

“Letter of Transmittal” has the meaning assigned to such term in Section 1.6.1.

“Liens” means, collectively, liens, pledges, security interests, claims, preemptive or subscriptive rights or other encumbrances or restrictions of any kind.

“Material Adverse Effect” with respect to a Person means an effect that: (a) is materially adverse to the business, assets, financial condition or results of operations of the Person and its Subsidiaries taken as a whole; or (b) materially and adversely affects the ability of the Person to consummate the Transactions on or by the Termination Date or to perform its material obligations under this Agreement; provided, however, that a Material Adverse Effect shall not be deemed to include the impact of or be deemed to occur as a result of any effects to the extent attributable to: (i) any changes in Laws or other changes affecting depository institutions generally; (ii) any changes to GAAP or regulatory accounting requirements, that do not have a materially more adverse effect on such party than that experienced by similarly situated financial services companies; (iii) any changes in general economic conditions; (iv) any changes in prevailing interest and deposit rates that do not have a materially more adverse effect on such party than that experienced by similarly situated financial services companies; (v) changes in financial, securities or credit markets; (vi) any changes in national or international political or social conditions, including any outbreak or escalation of major hostilities or acts of terrorism which involves the United States, declarations of any national or global epidemic, pandemic or disease outbreak, or the material worsening of such conditions threatened or existing as of the date of this Agreement; (vii) the impact of the public announcement of, pendency of or completion of the Transactions on relationships with customers and employees; (viii) any failure, in and of itself, to meet internal projections or forecasts (except that the facts or circumstances giving rise or contributing to such failure may nonetheless constitute, or be taken into account in determining whether there has been, a Material Adverse Effect); or (ix) any actions or omissions of a party taken at the written request of, or with the prior consent or written waiver of the other, or in contemplation of the Transactions as required or permitted under this Agreement, or as required under any regulatory approval received in connection with the Transactions.

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“Material Contract” has the meaning assigned to such term in Section 3.1.9(a).

“Maximum Transaction Expense Amount” means $11,695,000 (without regard to Taxes or Tax benefits).

“MBCA” means the Montana Business Corporations Act, as amended.

“Merger” has the meaning assigned to such term in Recital B.

“MJC Partners” means MJC Partners, LLC.

“Montana Commissioner” means the Commissioner of the Montana Division of Banking and Financial Institutions.

“Objection Notice” has the meaning assigned to such term in Section 4.1.10.

“Option Exercise Notice Deadline” has the meaning assigned to such term in Section 1.4.1.

“ordinary course of business” means an action taken, or omitted to be taken, in the ordinary course of such business in all respects that is materially consistent with past practice, without taking into account the transactions contemplated hereby including the Transactions.

“Outside Date” has the meaning assigned to such term in Section 7.1.

“Owned Real Estate” means all land, together with all buildings, structures, fixtures and improvements located thereon and all easements, rights of way, and appurtenances relating thereto, including approved and unopened branch offices, off-premises ATM locations and other facilities, owned by BOID or any BOID Subsidiary other than REO Property.

“Per Share Stock Consideration” means 1.1000 shares of GBCI Common Stock, which is subject to adjustment pursuant to Sections 7.2.2 and 7.3.2, and subject to further adjustment by an amount per share equal to the Stock Consideration Per Share Adjustment Amount, if any, pursuant to Section 4.14.2. Further, if GBCI declares or effects a stock dividend, reclassification, recapitalization, split-up, combination, exchange of shares or similar transaction between the Execution Date and the Effective Date, the Per Share Stock Consideration will be adjusted accordingly.

“Permitted Exceptions” has the meaning assigned to such term in Section 4.1.10.

“Person” includes an individual, corporation, partnership, association, limited liability company, bank, trust or unincorporated organization.

“Plan” has the meaning assigned to such term in Section 3.1.18(b).

“PPP” means the Paycheck Protection Program.

“Properties,” with respect to any party to this Agreement, means properties or other assets owned or leased by such party or any of its Subsidiaries, whether tangible or intangible.

“Proposed Dissenting Shares” means those shares of BOID Stock as to which shareholders have properly given notice of their intent to assert appraisal rights pursuant to the Appraisal Laws.

“Prospectus/Proxy Statement” has the meaning assigned to such term in Section 4.2.1(a).

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“Real Property” has the meaning assigned to such term in Section 3.1.5(c).

“Registration Statement” has the meaning assigned to such term in Section 4.2.1(a).

“REO Property” means “other real estate owned” (as defined by the FDIC).

“Requisite Regulatory Approvals” has the meaning assigned to such term in Section 4.3.

“Response Notice” has the meaning assigned to such term in Section 4.1.10.

“SEC” means the United States Securities and Exchange Commission.

“Securities Act” means the Securities Act of 1933, as amended, and the rules and regulations thereunder.

“Securities Laws” has the meaning assigned to such term in Section 3.1.3(d).

“Stock Consideration Per Share Adjustment Amount” has the meaning assigned to such term in Section 4.14.2.

“Subject Properties” has the meaning assigned to such term in Section 3.1.6(a)(i).

“Subsequent Bank Financial Statements” means the Bank’s unaudited internal balance sheets and related internal unaudited statements of income and changes in shareholder’s equity for each month after the Execution Date and before Closing or an earlier Termination Date prepared in accordance with Section 4.1.8.

“Subsequent BOID Financial Statements” means BOID’s (a) audited consolidated balance sheet as of December 31, 2024, and the related statements of income, cash flows and changes in shareholders’ equity, and (b) unaudited consolidated and parent-only balance sheets and related unaudited consolidated statements of income and changes in shareholders’ equity for each month after the Execution Date and before Closing or the Termination Date, as the case may be, prepared in accordance with Section 4.1.8.

“Subsidiary” with respect to any party to this Agreement means any Person in which such party, directly or indirectly, (a) owns or controls at least a majority of the outstanding capital stock or voting power of its outstanding securities or (b) has the power to appoint a general partner, manager or managing member or others performing similar functions.

“Superior Proposal” means, with respect to BOID and/or the Bank, any Acquisition Proposal that the board of directors of BOID in good faith concludes (after consultation with its financial advisors and outside counsel, and after taking into account, among other things, the terms and conditions of this Agreement (as it may be proposed to be amended by GBCI) and all legal, financial, regulatory, and other aspects of the proposal and the Person making the proposal), (a) would, if consummated, result in a transaction that is more favorable to BOID shareholders (in their capacities as shareholders), from a financial point of view, than the transactions contemplated by this Agreement (as it may be proposed to be amended by GBCI), and (b) is reasonably probable of being completed.

“Superior Proposal Notice Period” has the meaning assigned to such term in Section 7.4.7.

“Takeover Laws” and “Takeover Provisions” each has the meaning assigned to such terms in Section 3.1.19(b).

“Taxes” means all federal, state, local, non-U.S. and other income, gross receipts, sales, use, production, ad valorem, transfer, franchise, registration, profits, license, lease, service, service use, withholding,

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payroll, employment, unemployment, estimated, excise, severance, environmental, stamp, occupation, premium, property (real or personal), real property gains, windfall profits, customs, duties or other taxes, fees, assessments or charges imposed by a Governmental Authority in the nature of a tax of any kind whatsoever, together with any interest, additions, or penalties with respect thereto and any interest in respect of such additions or penalties.

“Tax Returns” means any return, declaration, report, claim for refund, information return or statement or other document required to be filed with or provided to any taxing authority in respect of Taxes, including any schedule or attachment thereto, and including any amendment thereof.

“Termination Date” means the date on which termination of this Agreement takes place under Article 7, if any.

“Title Companies” has the meaning assigned to such term in Section 4.1.10.