Recent actions by the U.S. government to support the banking sector won't stop loan loss levels from exceeding those reached during the Great Depression, banking analyst Mike Mayo of Calyon Securities said Monday.

Mayo, a long-time bear on the banking sector who recently left Deustche Bank, started Calyon's coverage of the U.S. banking sector with an "underweight" rating, indicating investors should minimize exposure in their portfolio.

Though the comments in Monday's report largely reiterate those made in a report Mayo released March 11 while still at Deutsche Bank, they underscore the lingering concerns among investors about the prospects for stabilization in the financial sector. Shares of banks have gained in recent weeks owing to the government intervention, hopes for improved earnings reports and thawing in credit markets, but uncertainty about the health of banks remains high.

Shares of banking sector stocks were leading the decliners in the S&P 500 index Monday morning. Shares of all 11 banks Mayo mentioned in his report were down by more than 3% each in early trading.

Mayo put "underweight" ratings on Bank of America Corp. (BAC), Citigroup Inc. (C) , JPMorgan Chase & Co. (JPM), Comerica Inc. (CMA), PNC Financial Services Group Inc. (PNC) and Wells Fargo & Co. (WFC). He assigned more- bearish "sell" ratings on BB&T Corp. (BBT), SunTrust Banks Inc. (STI), U.S. Bancorp (USB), Fifth Third Bancorp (FITB) and KeyCorp (KEY).

In recent trading, SunTrust shares were posting the biggest declines among those mentioned in the report, down 8.9% at $12.60. Bank of America shares were down 2.2% at $7.43, after falling as low as $7.14 earlier. Citigroup was down 3.5% at $2.75.

Mayo said loan losses for U.S. banks will likely increase to 3.5% from 2% by the end of 2010, due to ongoing problems in mortgage loans and increasing deterioration in credit cards and consumer, construction, commercial real estate and industrial loans. Under a stress scenario, loan losses could reach as high as 5.5%, Mayo said, compared with the 3.4% loss rate reached in 1934.

 
    Loans Not Marked Down Enough

Mayo titled his report "Seven Deadly Sins of Banking," and listed them as "greedy loan growth, a gluttony of real estate, lust for high yields, sloth-like risk management, pride of low capital, envy of exotic fees, and anger of regulators."

He said that the government won't be able to quickly resolve problem loans, which he said had only been marked by the banks that hold them to 98 cents on the dollar.

Furthermore, government efforts to support banks are a "Catch-22," he said, since being leinent with banks that have made mistakes will leave toxic assets on their balance sheets, while being tough on banks after the government stress tests are released in late April would force many of them to raise more dilutive equity capital, which would then hurt banking and lending activity.

"Thus, the industry may transition from the financial crisis (late stages of capital market write-downs) only to have more severe consequences of the economic crisis (loan losses)," Mayo wrote.

The report was Mayo's first since leaving the research department of Deutsche Bank AG (DB) for Calyon Securities USA Inc., an affiliate of the Asia Pacific-area research firm CLSA.

Also Monday, an analyst at BMO Capital Markets told clients in a research report that last month's rally in bank shares was unsustainable. Bank shares in the S&P 500 have rallied about 50% since the second week in March, when positive comments about profitability during January and February by Citigroup CEO Vikram Pandit and other bank CEOs set off a rally that was extended by further government actions to support banks.

Like Mayo, BMO Capital analyst Peter Winter said he was concerned by increasing deterioration in commercial real estate and commercial and industrial loans. Banks' capital reserves are inadequate given the rapid acceleration in problem assets and delinquent payments, he said.

-By Ed Welsch, Dow Jones Newswires; 201-938-5244; edward.welsch@dowjones.com