The S&P 500 fell 0.58% to 1,503 in midday trading Thursday.
The Dow Jones Industrial Average was off 0.68% to 13,892, while the Nasdaq was down 0.63% to 3,148.
The yield on a 10-year treasury bond fell 1.02% to 1.95%.
The price of gold was off 0.43% to $1,672 per ounce.
Shares of Allergan Inc. were off about 2% to $106. Allergan, which makes Botox and other drugs, had a recent market value of about $31.9 billion. Drug makers were generally down in afternoon trading Thursday. Allergan on Tuesday reported a fourth-quarter profit that missed analyst expectations and revenue in line with forecasts.
Irvine disk drive maker Western Digital Corp. was off about 2% to $47 for a market value of approximately $11.3 billion. Computer hardware makers were generally down in afternoon trading.
Shares of Irvine heart valve maker Edwards Lifesciences Corp. fell about 2% to $85 for a market value of about $9.7 billion. The company’s stock closed up 1.1% on Wednesday, following a 4% decline on Tuesday. Edwards reported better-than-expected fourth-quarter results on Monday, but a surge in sales of the company's transcatheter heart valves during the quarter has some analysts concerned sales of the device could slow in the second half of this year.