LONDON — For at least a quarter-century, the financial sector has grown far more rapidly than the economy as a whole, both in developed and in most developing countries. The ratio of total financial assets (stocks, bonds, and bank deposits) to gross domestic product (GDP) in the United Kingdom was about 100 percent in 1980, while by 2006 it had risen to around 440 percent. In China, financial assets went from being virtually nonexistent to well over 300 percent of GDP during this period.

As the size of the financial industry grew, so, too, did its profitability. The share of total profits of companies in the United States represented by financial firms rocketed from 10 percent in 1980 to 40 percent in 2006. Against that background, it is not surprising that pay in the financial sector soared. The City of London, lower Manhattan, and a few other centers became money machines that made investment bankers, hedge-fund managers, and private equity folk immoderately wealthy. University leaders like me spent much of our time persuading them to recycle a portion of their gains to their old schools.

For the last two years, things have been different. Many financial firms have shrunk their balance sheets dramatically, and of course some have gone out of business altogether. Leverage is down sharply. Investment banks with leverage of more than 30 times their capital in early 2007 are now down to little more than 10 times. Trading volumes are down, as is bank lending, and there have been major layoffs in financial centers around the globe.