U.S. banks haunted by mortgage demons that won't go away

These comments from banks provide a fresh reminder of the loose ends that remain from the housing bust that started five years ago. The threat of new expenses and litigation is dampening bank share prices, and the problem could linger for some time, analysts and experts said.

"This is not done yet," said Paul Miller, analyst with FBR Capital Markets. "There will be continued surprises in the industry."

The most pain will likely be felt by Bank of America, which said on Wednesday its total outstanding claims from investors surged more than 40 percent to about $22 billion in the second quarter. The bank's shares fell nearly 5 percent as investors worried about future losses and dropped again on Thursday.