By the end of 2010, about half of all commercial real estate mortgages will be underwater, said Elizabeth Warren, chairperson of the TARP Congressional Oversight Panel, in a wide-ranging interview on Monday.

Elizabeth Warren

“They are [mostly] concentrated in the mid-sized banks,” Warren told CNBC. “We now have 2,988 banks—mostly midsized, that have these dangerous concentrations in commercial real estate lending."