Will the bulls keep running this week? A number of big banks took big writedowns last week in a bid to clear their books of bad loans tied to this summer's credit crunch. Citigroup ( C), Merrill Lynch ( MER), Washington Mutual ( WM) and Deutsche Bank ( DB) were among big financial institutions taking big writedowns on the value of their loan and trading books. The losses were heavy, ranging as high as $5.5 billion in Merrill's case. But Wall Street's take on the banks' big hits was surprisingly upbeat, as stock indices hit new records. Citi CEO Charles Prince summed up the mood Monday, when he predicted Citi would "return to a normal earnings environment in the fourth quarter." Still, the banks aren't out of the woods yet. Their writedowns this quarter are based on the assumption they'll succeed in selling billions of dollars of loans still on their balance sheets. A return to normal also assumes that banks can sell the loans without taking too big a hit on pricing. Last week, many celebrated the sale of part of the loan package to finance Kohlberg Kravis Roberts' buyout of First Data. But a bigger deal lies ahead. According to sources familiar with the offering, the sale of loans to finance KKR and TPG's $32 billion buyout of Texas utility TXU ( TXU) is set to launch on Wednesday.