The S&P 500 fell 0.16% to 1,874.04 in afternoon trading Friday.
The Dow Jones Industrial Average was up 0.08% to 16,434.26, while the Nasdaq was off 0.69% to 4,321.79.
The yield on a 10-year Treasury bond rose 2.01% to 2.79%.
The price of gold was down 1.09% to $1,337.30 per ounce.
Irvine-based healthcare software maker Quality Systems Inc. was up about 3% to $17.61 for a market value of $1.06 billion. FBR Capital Markets upgraded the company's stock from "underperform" to "market perform."
Aliso Viejo-based software maker Smith Micro Software Inc. jumped about 48% to $2.59 a day after posting better-than-expected results for the fourth quarter. Smith Micro had a recent market value of $95.91 million.
Newport Beach-based Clean Energy Fuels Corp. rose about 3% to $9.53 for a market value of $851.64 million. Clean Energy Director John Herrington purchased 22,000 shares of the company's stock this week, according to a filing with the Securities and Exchange Commission.