The first ever GAO (Government Accountability Office) audit of the Federal Reserve was carried out in the past few months due to the Ron Paul, Alan Grayson Amendment to the Dodd-Frank bill, which passed last year. Jim DeMint, a Republican Senator, and Bernie Sanders, an independent Senator, led the charge for a Federal Reserve audit in the Senate, but watered down the original language of the house bill (HR1207), so that a complete audit would not be carried out.
Citigroup: $2.5 trillion ($2,500,000,000,000)
Morgan Stanley: $2.04 trillion ($2,040,000,000,000)
Merrill Lynch: $1.949 trillion ($1,949,000,000,000)
Bank of America: $1.344 trillion ($1,344,000,000,000)
Barclays PLC (United Kingdom): $868 billion ($868,000,000,000)
Bear Sterns: $853 billion ($853,000,000,000)
Goldman Sachs: $814 billion ($814,000,000,000)
Royal Bank of Scotland (UK): $541 billion ($541,000,000,000)
JP Morgan Chase: $391 billion ($391,000,000,000)
Deutsche Bank (Germany): $354 billion ($354,000,000,000)
UBS (Switzerland): $287 billion ($287,000,000,000)
Credit Suisse (Switzerland): $262 billion ($262,000,000,000)
Lehman Brothers: $183 billion ($183,000,000,000)
Bank of Scotland (United Kingdom): $181 billion ($181,000,000,000)
BNP Paribas (France): $175 billion ($175,000,000,000)
…and many many more including banks in Belgium of all places