The S&P 500 was down 0.8% in midday trading to 1,838.64.
The Dow Jones Industrial Average was down 0.7% to 15,911.48.
The NASDAQ was down 1.1% to 4,234.92.
The yield on a 10-year Treasury bond was down 1% to 1.72%.
The price of gold was up 0.1% to $1,199.
Laguna Hills-based Glaukos was up 1.5% to $15.03 and a $482 million market cap. Piper Jaffray initiated coverage on the maker of stents to treat glaucoma with an “outperform” rating and a $19 price target.
Irvine-based Lantronix Inc. was up 5.2% to $1.01 and a $15.3 million market cap. Shares had recovered slightly from a 17% decline over the last two trading sessions after the networking provider said it would take a pre-tax charge of $200,000 to $300,000 for “severance, lease termination and other associated costs” in its third quarter.