beneficial in the long run because they may require short-term adjustments that will depress stock prices. Because the market reflects the sum of millions of decisions by millions of investors, there is no good way to test this theory. In any event, Americans pride themselves on the efficiency of their stock market and other capital markets, which enable vast numbers of sellers and buyers to engage in millions of transactions each day. These markets owe their success in part to computers, but they also depend on tradition and trust -- the trust of one broker for another, and the trust of both in the good faith of the customers they represent to deliver securities after a sale or to pay for purchases. Occasionally, this trust is abused. But during the last half century, the federal government has played an increasingly important role in ensuring honest and equitable dealing. As a result, markets have thrived as continuing sources of investment funds that keep the economy growing and as devices for letting many Americans share in the nation's wealth.