Citigroup Inc., Bank of America Corp. and Wells Fargo & Co., set to report earnings this week, face investors groping for answers after evidence of flawed foreclosure documents triggered a selloff of U.S. bank stocks.

The banks plus JPMorgan Chase & Co. saw $49.3 billion in market value shaved off in the three days ended Oct. 15 amid concern that rising costs of faulty foreclosures will eat into profits. JPMorgan set aside $2.3 billion of reserves to cover mortgage repurchases or litigation expenses, including some for “mortgage-related matters,” the lender said Oct. 13.