Long-term interest rates and the dollar are rising after the Federal Reserve said it would reduce its bond purchases.
The Dow Jones industrial average was down 5 points, or 0.02 per cent, to 16,164 as of noon Thursday.
The Standard & Poor's 500 fell three points, or 0.2 per cent, to 1,808. Utilities stocks, which investors buy for their rich dividends, fell the most.
The Nasdaq composite fell 13 points, or 0.3 per cent, to 4,057.
Bond prices fell, sending yields higher. The yield on the 10-year Treasury note rose to 2.93 per cent.
Facebook fell 2 per cent after the company said it will sell 70 million shares, including more than 41 million held by founder and CEO Mark Zuckerberg.