The S&P 500 was up 0.8% in midday trading to 2,095.78.
The Dow Jones Industrial Average was up 0.6% to 17,763.75.
The Nasdaq was up 1.1% to 5,108.93.
The yield on a 10-year Treasury bond was up 0.8% to 2.17%.
The price of gold was down 0.5% to $1,136.
Irvine-based Endologix Inc. was up 5.4% to $9 and a $610 million market cap on high volume. The medical device maker’s shares had by midday traded at about double its 90-day average.
Newport Beach-based Alliance Healthcare Services Inc. was up 11.2% to $9.41 and a $100 million market cap. The radiology clinics operator had traded an above-average number of shares by midday. It’s scheduled to report quarterly results after markets close on Thursday.