The S&P 500 was down 1.18% to 1,823.15 in afternoon trading Friday.
The Dow Jones Industrial Average fell 1.28% to 16,164.53, while the Nasdaq slipped 0.99% to 4,200.88.
The yield on a 10-year Treasury bond was down 2.76% to 2.78%.
The price of gold was up 1.95% to $1,262.70 per ounce.
Irvine healthcare software maker Quality Systems Inc. was up about 3% to $18.95, despite missing on analyst projections for its December quarter released before market open. Quality had a recent market value of $1.14 billion.
Irvine drug maker Allergan Inc. slipped about 2% to $116.59 for a market value of $34.65 million. Actavis Inc. on Wednesday said it filed for patent certification for a generic to Allergan's dry eye drug Restasis.
Huntington Beach-based BJ's Restaurants Inc. was off about 2% to $28.98, with restaurant operators generally mixed on Thursday. BJ's had a recent market value of $818.02 million.