The S&P 500 was down 0.5% in midday trading to 2,804.13.
The Dow Jones Industrial Average declined 0.3% to 25,574.13.
The Nasdaq dropped 0.7% to 7,635.61.
The yield on a 10-year Treasury bond fell 1.4% to 2.38%.
The price of gold ticked 0.3% lower to $1,311 an ounce.
The price of oil fell 1.1% to $59.26 a barrel.
San Clemente-based Glaukos Corp. (NYSE: GKOS) was down 4.5% to $76.31 and a $2.8 billion market cap. Shares in the maker of products to treat glaucoma are still up about 40% year-to-date.
William Lyon Homes (NYSE: WLH) in Newport Beach was up 4.5% to $15.85 and a $576 million market cap. The homebuilder’s shares are up more than 30% year-to-date.