The S&P 500 slipped 1.02% to 1,614.80 in midday trading Wednesday.
The Dow Jones industrial average was down 1.14% to 15,005.21, while the Nasdaq was off 0.94% to 3,412.95.
The yield on a 10-year Treasury bond fell 2.25% to 2.09%.
The price of gold rose 0.26% to $1,400.90 per ounce.
Aliso Viejo-based Avanir Pharmaceuticals Inc. rose about 10% to $3.70 for a market value of $536.9 million. The Food and Drug administration approved an expedited development process for Avanir’s AVP-786 drug candidate that "has the potential to substantially reduce the cost and time to market," Avanir Chief Scientific Officer Joao Siffert said in a statement.
QLogic Corp. fell back about 3% to $9.96 after closing up 3% on Tuesday. The company, which had a recent market value of $886.4 million, announced a restructuring plan on Tuesday that includes a reduction in its workforce.