A war takes place; an earthquake occurs; a flood of a magnitude not seen in a hundred years washes over the land; a cartel falls apart; oil prices quadruple; tax laws change, and the market in which you had an open position, or even hedged, moves in a magnitude not only unforeseen, but totally outside past models. They always do. You are in trouble.

"Testimony Before the U.S. House of Representatives Committee on Banking, Finance and Urban Affairs.", October 1 1998