Located in Manhattan, New York, this exchange ranks in the top half-dozen US exchanges in terms of trading volume. Its activities go back to the 1849 gold rush, and it was known until 1921 as the Kerb Exchange because trading took place outdoors (at the kerb). The American Stock Exchange trades small and medium-sized companies' shares, whereas the New York Stock Exchange carries the big-name, mature companies. Abbrev. AMEX.