How should one read JPMorgan’s Whale Report? I suppose “not” is an acceptable answer; the Whale’s credit derivatives losses at JPMorgan’s Chief Investment Office are old news by now, though perhaps his bones point us to the future. One way to read it is as a depressing story about measurement. There were some people and whales, and there was a pot of stuff, and the people and whales sat around looking at the stuff and asking themselves, and each other, “what is up with that stuff?” The stuff was in some important ways unknowable: you could list what the stuff was, if you had a big enough piece of paper, but it was hard to get a handle on what it would do. But that was their job. And the way you normally get such a handle, at a bank, is with a number, or numbers, and so everyone grasped at a number.
The problems were (1) the numbers sort of sucked and (2) everyone used a different number. Here I drew you a picture:1
Everyone tried to understand the pool of stuff through one or two or three numbers, and everyone failed dismally through some combination of myopia and the fact that each of those numbers was sort of horrible or tampered or both, each in its own special way. Starting with:
VaR: Value-at-risk is the #1 thing that people talk about when they want to talk about measuring risk. To the point that, if you want to be all “don’t look at one number to measure risk, you jerks,” VaR is the one number you tell the jerks not to look at. Read more »