Any exchange using Dwolla CSVs over the past two months almost certainly has loses to the order of 3 to 9% of their volume.
Adam
This could mean that some exchanges no longer have the funds to cover all their liabilities, and are now operating on a "fractional reserve" model where they just hope everybody won't withdraw their money all at once. Kinda scary.
This is why I try not to leave any more money than I have to on the exchanges. There is nobody looking over their shoulder to make sure they aren't making big loans to themselves, writing off big losses, etc, all while naively intending to pay the money back "someday, with our future profits"