The S&P 500 rose 0.14% to 1,886.60 in afternoon trading Thursday.
The Dow Jones Industrial Average fell 0.01% to 16,578.90, while the Nasdaq rose 0.61% to 4,139.59.
The yield on a 10-year Treasury bond was off 1.44% to 2.61%.
The price of gold slipped 0.90% to $1,284.30 per ounce.
Costa Mesa networking equipment maker Emulex Corp. slumped about 30% to $5.03 for a market value of $406.74 million. The company guided below consensus estimates on revenue and earnings for the current quarter.
Irvine-based disk drive maker Western Digital Corp. fell about 6% to $82.74, a day after providing an outlook for the current quarter that missed analyst estimates. Western Digital had a recent market value of $19.55 billion.
Aliso Viejo-based networking equipment maker QLogic Corp. was down about 6% to $10.48 for a market value of $942.17 million. The company is expected to report its fourth quarter and full-year results after market close today.
Aliso Viejo-based drug maker Avanir Pharmaceuticals Inc. fell back about 9% to $4.53 for a market value of $689.90 million. The company's shares climbed 46% on Wednesday after a federal court ruled in Avanir's favor on a patent lawsuit.
Irvine-based medical device maker Endologix Inc. was up about 6% to $13.45 after reporting better-than-expected first-quarter results. Endologix had a recent market value of $859.04 million.