Stocks fell in volatile trading after the Federal Reserve decided against raising interest rates again but left open the possibility of a third rate increase later this year.

The Dow Jones industrial average closed 0.64 lower at 10,400.59 after swinging from a 106-point gain to a 124-point loss over the final two hours.

Technology shares lifted the Nasdaq composite index 3.70, to 2799.67, but most broad-market indexes also turned lower in the afternoon, cresting just as the Fed was set to announce the outcome of a meeting on inflation and interest rates. The Standard & Poor's 500 index fell 3.25, to 1301.35.

Telecommunications stocks dominated today's most-active list amid news that MCI WorldCom had sealed an agreement to acquire long-distance rival Sprint for $115 billion in what would be the largest corporate takeover in history.

MCI WorldCom's shares slid 6 percent, falling by 3-11/16, to 67-15/16, as the most active Nasdaq issue, while Sprint fell 2, to 58 7/8, in heavy trading on the NYSE. But among other leading telecom names, AT&T rose 1 1/4, to 45, on the NYSE to help bolster the Dow, and Qwest Communications rose 9/16, to 33 1/4, in Nasdaq trading.

American Express also helped the Dow, rising 3 1/8, to 140-11/16, after the firm announced plans to launch a brokerage unit with online trading and access to financial advisers.