The short answer: Alot.
The longer answer depends upon the bank’s derivative exposure. Chris includes this handy chart to help you figure out just what that cap need might be:
Sources: FDIC/IRA Bank Monitor; Q1 2008 data shown in “bank only” rollup.
WTF? $90 Trillion dollars derivative exposure for JPMorgan ? No wonder the Fed "rescue" of Bear Stearns was via JPM — it was their own derivative exposure that was at risk.
Memo to the President-Elect; How Much Capital Does a Bank Need?
Institutional Risk Analyst, August