The S&P 500 rose 0.14% to 1,822.20 in afternoon trading Wednesday.
The Dow Jones Industrial Average was down 0.06% to 15,984.65, while the Nasdaq was up 0.38% to 4,206.86.
The yield on a 10-year Treasury bond rose 1.73% to 2.76%.
The price of gold was up 0.38% to $1,294.70 per ounce.
Anaheim-based drug maker Questcor Pharmaceuticals Inc. rose about 4% to $69.90 for a market value of $4.12 billion. The company's stock is up about 21% so far this year. It's expected to report results for the fourth quarter on Feb. 25.
Newport Beach-based Clean Energy Fuels Corp. was off about 3% to $9.56 for a market value of $854.26 million. Chief Executive Andrew Littlefair held a conference call Monday to provide an update and commentary on use of liquified natural gas for trucks following recent negative press surrounding the subject. Clean Energy shares are down about 23% so far this year.