Investors are back to worrying about banks.

Long-present unease about soured loans bubbled over yesterday after Bank of America Corp. said it set aside $13.4 billion to cover lending losses, even as it posted a profit for the first quarter, and as anxiety grew about the results of the government's "stress tests" to determine if banks will need more government bailout money.

Joe Saluzzi, co-head of equity trading at Themis Trading LLC, said traders are skeptical about bank earnings and believe the better-than-expected profit reports may be disguising problems.