The S&P 500 rose 0.28% to 1,883.06 in afternoon trading Monday.
The Dow Jones Industrial Average was up 0.03% to 16,496.74, while the Nasdaq was up 0.75% to 4,121.18.
The yield on a 10-year Treasury bond fell 0.16% to 2.51%.
The price of gold rose 0.12% to $1,295.00 per ounce.
Anaheim-based drug maker Questcor Pharmaceuticals Inc. rose about 3% to $92.45 for a market value of $5.47 billion. The company's stock is up about 63% so far this year.
Irvine-based medical device maker Endologix Inc. was up about 4% to $12.77 for a market value of $817.45 million. Canaccord recommended purchase of the company's stock on expected revenue growth in the back half of the year.