The S&P 500 was flat in midday trading at 1,999.81.
The Dow Jones Industrial Average was up 0.3% to 17,062.48.
The NASDAQ was down 0.4% to 4,700.56.
The yield on a 10-year Treasury bond was up 1.7% to 1.91%.
The price of gold was down 0.4% to 1,265.80.
Lake Forest-based Del Taco Restaurants Inc. was down 2% to $10.25 and a $398 million market cap. The fast food chain reported earnings for its most recent quarter, and guided full-year results, below analyst expectations.
Costa Mesa-based El Pollo Loco Holdings Inc. was up 5% to $15 and a $574 million market cap on high volume. The fast food chain is scheduled to report results Thursday after markets close.
Irvine-based Habit Restaurants Inc. was up 8% to $20.64 and a $555 million market cap. The fast casual burger chain had by midday traded shares at twice its 90-day average.
Anaheim-based Bridgford Foods Corp. was up 10% to $10 and a $91 million market cap. The food maker reported a net profit in its most recent quarter compared with a loss in the same period a year ago.
Tustin-based Peregrine Pharmaceuticals Inc. was up 13% to 48 cents and a $111 million market cap. The cancer treatment maker said a new manufacturing facility doubles its production capacity and could add up to $40 million in annual revenue.
Irvine-based CombiMatrix Corp. was up 27% to $7.10 and a $6 million market cap on high volume. The DNA testing company had traded shares by midday at about 11 times its 90-day average.