(Reuters) -The Nasdaq and S&P 500 fell on Wednesday as investors sold tech stocks and moved into less highly valued sectors, as they also awaited remarks from Federal Reserve officials at their Jackson Hole symposium this week.

Wall Street's main indexes fell on Wednesday, with a selloff in tech stocks driving the Nasdaq to a two-week low as caution prevailed ahead of the Federal Reserve's highly anticipated Jackson Hole symposium this week.

Futures for the main stock indexes retreated before the market opened on Wednesday, continuing to fall after a tech selloff in the previous session. Minutes from the Federal Reserve’s last meeting and earnings from big-name retailers could push them in either direction later in the day.

The U.S. dollar hovered below a one-week high on Thursday and Asian stock markets were mixed as investors braced for three days of potentially market-moving news from the Federal Reserve's annual symposium in Jackson Hole.

Stocks often rise the week of the Fed’s big Jackson Hole gathering. Don’t count on it this year. Why a ‘wall of money’ is unlikely to flood into stocks when the Fed cuts rates, this Goldman strategist says.

Software maker Palantir (NASDAQ: PLTR) plunged more than 9%, making it the S&P 500's weakest performer. The Dow Jones Industrial Average (DJINDICES: ^DJI) bucked the trend, edging up 10.45 points, or 0.