Wall Street was lower on Wednesday, led by declines in technology and defensive stocks as investors weighed up the possibility of a rate hike in the coming months.
The market is awaiting Federal Reserve Chair Janet Yellen's speech in Jackson Hole, Wyoming on Friday when she is expected to give a steer on the direction of monetary policy.
Recent hawkish comments from some Fed officials, including Vice Chairman Stanley Fischer, have raised expectations that Yellen might signal a hike in September.
Eight of the 10 major S&P 500 indexes were trading lower. The financial sector, which stands to benefit from higher rates, was flat.
The bigger decliners were utilities, consumer staples and telecom services, defensive sectors that have led Wall Street's rally this year as expectations of a rate hike kept getting pushed out.
While Wall Street is trading near records levels, volumes have been below average in the past few sessions as the U.S. earnings season winds down and traders avoid major bets until a clearer picture on monetary policy emerges.
"Caution is certainly warranted before Yellen's speech. We know it's going to move the market, we just don't know which way," said Matthew Tuttle, chief investment officer of Tuttle Tactical Management in Connecticut.
"The biggest risk right now is that she comes out and makes it look like September is squarely on the table."
At 12:26 p.m. ET (1626 GMT), the Dow Jones Industrial Average was down 25.1 points, or 0.14 percent, at 18,522.2.
The S&P 500 was down 3.54 points, or 0.16 percent, at 2,183.36.
The Nasdaq Composite index was down 7.10 points, or 0.13 percent, at 5,252.98.
The technology index, which propelled the Nasdaq to an intraday record on Tuesday, was down 0.34 percent and the biggest drag among the 10 S&P sectors.
Express Inc plunged 24.7 percent after the apparel maker slashed its full-year earnings outlook.
Garmin was the top percentage loser on the S&P, falling 4 percent after Goldman Sachs downgraded the stock.
Declining issues outnumbered advancing ones on the NYSE by 1,810 to 1,046. On the Nasdaq, 1,376 issues rose and 1,332 fell.
The S&P 500 index showed 15 new 52-week highs and no new lows, while the Nasdaq recorded 79 new highs and 12 new lows. (Reporting by Yashaswini Swamynathan in Bengaluru; Editing by Savio D'Souza)