The S&P 500 was down 0.6% in midday trading to 2,051.23.
The Dow Jones Industrial Average was down 0.5% to 17,657.08.
The NASDAQ was down 0.7% to 4,728.05.
The yield on a 10-year Treasury bond was down 0.9% to 1.78%.
The price of gold was down 1.3% to $1,275.
Laguna Hills-based Glaukos Corp. was up 24% to $24.58 and a $796 million market cap. The maker of treatments for glaucoma handily beat analyst expectations on revenue and profit and provided fiscal year guidance above the current consensus.
Newport Beach-based American Vanguard Corp. was down 15% to $13.83 and a $404 million market cap. The chemicals maker missed analyst expectations on revenue. Roth Capital downgraded its shares to “neutral” with a $14.50 price target.
Lake Forest-based Del Taco Restaurants Inc. was up 5% to $9.90 and a $383 million market cap. Shares in the fast food chain have risen about 12% in the last two trading sessions after a positive quarterly report.