Investors squaring postions in event of weekend agreement to stave off a possible U.S. default.

Investors remain worried about critical issue of U.S. debt ceiling. | Boehner says U.S. on path to default if Obama won't negotiate | Stakes start rising over Washington gridlock

A shutdown of the U.S. government could spark a major equity decline.

Latest version of the fiscal follies playing out in Washington contains overblown threats for investors.

By Chuck Mikolajczak

NEW YORK, Sept 18 (Reuters) - U.S. stocks rallied to record highs on Wednesday after the Federal Reserve surprised investors and decided against trimming its bond-buying stimulus program that helped fuel Wall Street's rally of more than 20 percent this year.

Stocks were modestly lower before the announcement, but after the Fed statement the Dow and S&P 500 indexes quickly climbed to record highs after the central bank said it would continue buying bonds at an $85 billion monthly pace for now.

Threatens an end to a six-day run of gains for the S&P 500.

Syria worries spur caution; U.S. stocks close little changed in choppy trade.

Four-fifths of that was pulled from the SPDR S&P 500 ETF as jittery investors worried about the stock market.

Investors hold off making large bets before a long weekend in the U.S. with the situation in Syria still uncertain.

U.S. stocks hit session lows after release of minutes from the U.S. Fed's July policy-setting meeting.