Technical problems at the

American Stock Exchange

delayed the open of stock trading Monday morning.

An exchange spokeswoman said the problems were rectified by about 1 p.m. EST.

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The system's problems affected trading in company stocks and exchange-traded funds, some of the most heavily traded shares on the American. The technical glitch did not impact options trading.

Exchange-trade funds, or ETFs, are special stocks that trade an entire index or sector. The stocks are like mutual funds. But unlike shares of mutual funds, ETFs can be traded throughout the day.