The S&P 500 was down 0.4% in midday trading to 2,181.16.
The Dow Jones Industrial Average was down 0.4% to 18,569.62.
The NASDAQ was down 0.5% to 5,236.73.
The yield on a 10-year Treasury bond was up 1% to 1.57%
The price of gold was up 0.6% to $1,355.
Laguna Hills-based Glaukos Corp. was down 7% to $31.30 and a $1 billion market cap on high volume. The company makes products to treat glaucoma.
Santa Ana-based Collectors Universe Inc. was down 5% to $20.80 and a $185 million market cap on above-average volume. The company provides collectibles authentication and grading services.
Irvine-based Cryoport Inc. was down 2.5% to $1.95 and a $29 million market cap. The cryogenic services company lost $3.9 million in its most recent quarter compared with $1.9 million in the same period last year.