A deal to rescue insolvent German retailer Karstadt from insolvency neared completion late Thursday after a final group of Karstadt creditors agreed to a takeover plan by billionaire investor Nicholas Berggruen, the Highstreet real estate consortium said Thursday.

The agreement between Berggruen and a group of Karstadt's subordinate debt holders marked the last step in several months of heated negotiations between Berggruen and creditors to finalize his takeover plan. The iconic German retailer, which employs more than 25,000 staff around Germany, risked liquidation if Berggruen and Karstadt's creditors had failed to reach an agreement before a midnight deadline set by its insolvency administrator.

An Essen court is expected to approve the takeover plan at a hearing Friday.

The subordinate, mezzanine debt holders were part of the Highstreet real estate investment vehicle, a major owner of Karstadt properties led by Goldman Sachs Group. Inc. (GS).

Another key group of Karstadt's debt holders, representing one of the senior tranches of a real estate investment vehicle which owns Karstadt properties, agreed to Berggruen's plan earlier Thursday.

Berggruen reached a basic agreement with most of Karstadt's key senior bondholders at a previous meeting in July in London, but needed the additional meeting Thursday to finalize technical details before signing.

The German-American investor has since June haggled over the terms of his deal with creditors ranging from Germany's Valovis Bank and Highstreet.

The negotiations have centered on reductions to Karstadt property rents and plans to reorganize Karstadt into separate units including sport and premium stores.

-By William Launder, Dow Jones Newswires; +49(0)6929725515; william.launder@dowjones.com