A lot has been said and written, for instance, about the corrupting effects on Wall Street of gigantic bonuses. What happened inside the major Wall Street firms, though, was more deeply unsettling than greedy people lusting for big checks: leaders of public corporations, especially financial corporations, are as good as required to lead for the short term.

Richard Fuld, the former chief executive of Lehman Brothers, E. Stanley O’Neal, the former chief executive of Merrill Lynch, and Charles O. Prince III, Citigroup’s chief executive, may have paid themselves humongous sums of money at the end of each year, as a result of the bond market bonanza. But if any one of them had set himself up as a whistleblower  had stood up and said “this business is irresponsible and we are not going to participate in it”  he would probably have been fired. Not immediately, perhaps. But a few quarters of earnings that lagged behind those of every other Wall Street firm would invite outrage from subordinates, who would flee for other, less responsible firms, and from shareholders, who would call for his resignation. Eventually he’d be replaced by someone willing to make money from the credit bubble.

OUR financial catastrophe, like Bernard Madoff’s pyramid scheme, required all sorts of important, plugged-in people to sacrifice our collective long-term interests for short-term gain. The pressure to do this in today’s financial markets is immense. Obviously the greater the market pressure to excel in the short term, the greater the need for pressure from outside the market to consider the longer term. But that’s the problem: there is no longer any serious pressure from outside the market. The tyranny of the short term has extended itself with frightening ease into the entities that were meant to, one way or another, discipline Wall Street, and force it to consider its enlightened self-interest.

The credit-rating agencies, for instance.

Everyone now knows that Moody’s and Standard & Poor’s botched their analyses of bonds backed by home mortgages. But their most costly mistake  one that deserves a lot more attention than it has received  lies in their area of putative expertise: measuring corporate risk.

Over the last 20 years American financial institutions have taken on more and more risk, with the blessing of regulators, with hardly a word from the rating agencies, which, incidentally, are paid by the issuers of the bonds they rate. Seldom if ever did Moody’s or Standard & Poor’s say, “If you put one more risky asset on your balance sheet, you will face a serious downgrade.”

The American International Group, Fannie Mae, Freddie Mac, General Electric and the municipal bond guarantors Ambac Financial and MBIA all had triple-A ratings. (G.E. still does!) Large investment banks like Lehman and Merrill Lynch all had solid investment grade ratings. It’s almost as if the higher the rating of a financial institution, the more likely it was to contribute to financial catastrophe. But of course all these big financial companies fueled the creation of the credit products that in turn fueled the revenues of Moody’s and Standard & Poor’s.

These oligopolies, which are actually sanctioned by the S.E.C., didn’t merely do their jobs badly. They didn’t simply miss a few calls here and there. In pursuit of their own short-term earnings, they did exactly the opposite of what they were meant to do: rather than expose financial risk they systematically disguised it.