its payment based.
And home sales have nothing to do with bank assets. Its not pleasant, and the market needs to stabilize so that credit will free up etc...but whats on their books is history..sales and current pricing now don't have that much of an impact.
I would be more concerned about them dumping homes significantly below value after foreclosure instead of working to re-term loans. That's giving away my money as opposed to at least some attempt to preserve it.