The S&P 500 increased 0.1% in midday trading to 2,735.26.
The Dow Jones Industrial Average declined 0.2% to 24,956.96.
The Nasdaq was unchanged at 7,397.05.
The yield on a 10-year Treasury bond rose 0.2% to 3.07%.
The price of gold was up 0.2% to $1,293.
Newport Beach-based Clean Energy Fuels Corp. (Nasdaq: CLNE) jumped 8.4% to $2.70 and a $412 million market cap on volume twice its daily average of the past three months. Shares of the supplier of renewable natural gas and fueling stations have doubled since a 52-week low in March.
Biolase Inc. (Nasdaq: BIOL) in Irvine was up 9.4% to $1.28 and a $131 million market cap on high volume. Shares of the dental laser maker are still down 17% since a 5-for-1 reverse stock split on May 10.