I've been playing with the math on sub prime. I can easily come up with $50 billion of total announced write-downs - and I'm sure that I don't have them all. However, I'm skeptical of two things: first, that the losses will really be this big; and second, that the losses are entirely related to mortgages. If we assume that the typical sub-prime loan is $250,000, then 200,000 homeowners would have to default, pay nothing, and the houses sell for less than the disposal cost - i.e. - so that the bank receives none of its principal back, for the losses to be $5o billion. I can see more than 200K homeowners defaulting, but it is harder to imagine that they (that is, the lenders) get zero proceeds from foreclosure sales. In researching this, one thing kept coming up - it isn't clear that all the loans that are being reserved are related to mortgages. The terms in the bank and security firm press releases and filings are more than a little murky. So, don't be surprise...