The S&P 500 was down 0.4% in midday trading to 2,158.87.
The Dow Jones Industrial Average was down 0.3% to 18,260.76.
The NASDAQ was down 0.3% to 5,297.52.
The yield on a 10-year Treasury bond rose 0.4% to 1.62%.
The price of gold fell 0.25 to $1,314.
Irvine-based CalAmp Corp. was down 2% to $13.67 and a $495 million market cap. Two analysts downgraded shares since the wireless connectivity company reported lower earnings and gave weaker guidance last week.
Costa Mesa-based El Pollo Loco Holdings Inc. was down 3.5% to $12.16 and a $467 million market cap on above-average volume. The company operates a fast food chicken chain.
Anaheim-based Willdan Group Inc. was up 3.2% to $18.11 and a $150 million market cap on high volume. The company provides engineering services.