That's the thing I don't get at all, they had what, something like 160b in deposits - they could've kept 150b in bills, ten billion in Treasury bonds, and still made millions to hundreds of millions per year ostensibly risk free - surely enough to keep a ledger balanced. The bet on mbs at historic lows seemed like a pennies in front of steam rollers play
Bob, responsible for risk management, goes to the boss and says "Hey here is the plan that makes us $X and keeps us at acceptable risk of interest rate changes." Jim, the boss says "Jeez $X isn't very much money, our shareholders expect returns! If we changed our portfolio like this we'd make $Y. You are being a debbie downer, bond prices won't collapse and even if they do we just hold them to maturity and we are fine. We simply can't leave this much money on the table."
