Wall Street edged lower on Wednesday after two Federal Reserve officials hinted at an interest rate hike as soon as this month.
Kansas City Fed President and voting member Esther George said the U.S. labor market could already be at full strength, one of the key conditions set by the Fed for considering an interest rate hike.
Richmond Fed President Jeffrey Lacker said the case for a rate hike in September was strong.
The Fed releases its Beige Book, a summary of commentary on economic conditions, at 2:00 p.m. ET (1800 GMT).
U.S. stocks have been trading in a tight range in the past few months, with the S&P 500 not moving more than 1 percent in either direction on a daily basis since July 8.
"We've had very quiet market activity for a couple of months ... And a lot of uncertainty on policy," said Tim Courtney, chief investment officer at Exencial Wealth Advisors.
Investors will wait until they get more clarity on presidential elections, the quality of third-quarter earnings and the timing of the next rate hike, Courtney said.
At 12:33 p.m. ET (1633 GMT), the Dow Jones Industrial Average was down 57.15 points, or 0.31 percent, at 18,480.97.
The S&P 500 was down 6.65 points, or 0.3 percent, at 2,179.83.
The Nasdaq Composite was down 12.45 points, or 0.24 percent, at 5,263.46, after touching an intraday high.
Nine of the 10 major S&P 500 indexes were lower, with the consumer staples index falling the most in six weeks.
Whole Foods fell 5.4 percent and weighed the most on the index after smaller rival Sprouts Farmers Market painted a bleak picture for grocers with a disappointing quarterly outlook.
Apple shares were down 0.12 percent at $107.62, after the biggest company by market value launched the new iPhone.
Retrophin soared 34.25 percent after the company said its drug to treat a kidney disorder met the main goal of a mid-stage study. The stock was the top percentage gainer on the Nasdaq.
Advancing issues outnumbered decliners on the NYSE by 1,519 to 1,382. On the Nasdaq, 1,528 issues rose and 1,242 fell.
The S&P 500 index showed 22 new 52-week highs and one new lows, while the Nasdaq recorded 105 new highs and 14 new lows. (Reporting by Yashaswini Swamynathan in Bengaluru; Editing by Anil D'Silva)