The Jester Courts

One of the characters in the classic 1939 film “Stagecoach” is a banker named Gatewood who lectures his captive audience on the evils of big government, especially bank regulation — “As if we bankers don’t know how to run our own banks!” he exclaims. As the film progresses, we learn that Gatewood is in fact skipping town with a satchel full of embezzled cash.

As far as we know, Jamie Dimon, the chairman and C.E.O. of JPMorgan Chase, isn’t planning anything similar. He has, however, been fond of giving Gatewood-like speeches about how he and his colleagues know what they’re doing, and don’t need the government looking over their shoulders. So there’s a large heap of poetic justice — and a major policy lesson — in JPMorgan’s shock announcement that it somehow managed to lose $2 billion in a failed bit of financial wheeling-dealing.

Just to be clear, businessmen are human — although the lords of finance have a tendency to forget that — and they make money-losing mistakes all the time. That in itself is no reason for the government to get involved. But banks are special, because the risks they take are borne, in large part, by taxpayers and the economy as a whole. And what JPMorgan has just demonstrated is that even supposedly smart bankers must be sharply limited in the kinds of risk they’re allowed to take on.

… What did JPMorgan actually do? As far as we can tell, it used the market for derivatives — complex financial instruments — to make a huge bet on the safety of corporate debt, something like the bets that the insurer A.I.G. made on housing debt a few years ago. The key point is not that the bet went bad; it is that institutions playing a key role in the financial system have no business making such bets, least of all when those institutions are backed by taxpayer guarantees.

For the moment Mr. Dimon seems chastened, even admitting that maybe the proponents of stronger regulation have a point. It probably won’t last; I expect Wall Street to be back to its usual arrogance within weeks if not days.

But the truth is that we’ve just seen an object demonstration of why Wall Street does, in fact, need to be regulated. Thank you, Mr. Dimon.