The Nasdaq was down 0.51% to 3,121 in midday trading Friday, while the Dow Jones Industrial Average was off 0.41% to 13,431.
The S&P 500 fell 0.48% to 1,440.
The yield on a 10-year treasury bond was up 0.43% to 1.65%.
The price of gold was down 0.34% to $1,775 per ounce.
Shares of Irvine-based healthcare software maker Quality Systems Inc. rose about 7% to $19 for a market value of $1 billion.
Tustin drug developer Peregrine Pharmaceuticals Inc. continued its slide, with shares down about 10% to $1 for a market value of $106 million. Peregrine’s stock this week has been a rollercoaster ride, beginning with Monday's 76% drop after major discrepancies were found in its trial data for lung-cancer treatment bavituximab.