M&T Bank News Spells Trouble for Downey Financial

See this Calculated Risk post. M&T Bank - which is partially owned by Warren Buffett - is being forced to markdown and repurchase its Alt-A loans.

From the MTB 8-K: "Management of M&T believes that the value of the Alt-A residential mortgage loans it holds is greater than the amount implied by the few bidders presently active in the market. As a result, $883 million of Alt-A loans previously held for sale... were transferred in March to M&T’s held-for-investment residential mortgage loan portfolio."

Does anyone think that a bank owned by Buffett does worse underwriting than Downey? What does this imply about the value of Downey's portfolio of Alt-A loans?