While a handful of smaller U.S. exchanges exist today, they tend to specialize in options, and, notably in the case of the American Stock Exchange, exchange-traded funds. (See story, p. 47.) A quirk in a 1975 U.S. securities law has allowed the regional markets to trade shares listed on the New York and American exchanges in a way that is attractive to big brokerage houses, keeping the smaller bourses alive on life support.

FORBES: World Markets