Share maket is a zero sum game, Profit of one is the loss of other, nett nett is zero.
So is most of the deals, purchase, loans etc. so banks have lost money, but that money has gone into somebodys' hands due to bad loans only.
But, the same is not true with capital Erosion . incase of fall in market or fall in currency values, where the money has eroded due to fall in price/value, here it is not a zero sum game. like one mans profit is not another mans loss. this is Erosion of capital, which is why most banks went bankrupt, not only beacuse of bad loans only.
Most banks had undue exposure to capital market and lost money due to Marked to Market losses, and went bankrupt. Please recall the steep fall we had in ICICI bank share prices when they reported MTM losses.