The S&P 500 declined 0.3% in midday trading to 2,864.24.
The Dow Jones Industrial Average fell 0.3% to 26,536.92.
The Nasdaq dropped 0.2% to 7,487.54.
The yield on a 10-year Treasury bond jumped 1.3% to 2.70%.
The price of gold was down 0.8% to $1,341.
Irvine-based ChromaDex Corp. (Nasdaq: CDXC) fell 4.5% to $5.20 and a $279 million market cap. The company sponsored a gathering of scientific leaders at the 2018 NAD+ Summit in San Diego Jan. 26-28. The shares have more than doubled since March.
Anaheim-based Bridgford Foods Corp. (Nasdaq: BRID) increased 6.1% to $17.35 and a $157 million market cap on daily volume twice its 90-day average. Bridgford, which makes frozen and snack food products, has risen about 39% since Jan. 10.