The S&P 500 increased 0.7% in midday trading to 2,598.89.

The Dow Jones Industrial Average rose 0.8% to 23,610.63.

The Nasdaq jumped 1% to 6,860.10.

The yield on a 10-year Treasury bond fell 0.5% to 2.36%.

The price of gold climbed 0.4% to $1,280.

HEALTHCARE

San Clemente-based Glaukos Corp. (NYSE: GKOS) dropped 8.6% to $25.79 and a $891 million market cap. The company, a maker of products to treat glaucoma, hit a 52-week low today and is down 39% since September when it cut its annual revenue and profit forecast.

Irvine-based ChromaDex Corp. (Nasdaq: CDXC) increased 5.4% to $6.85 and a $330 million market cap. Shares of the maker of ingredients for nutritional supplements have more than doubled in the past two months following stock purchases by big name investors such as Hong Kong billionaire Li Ka-Shing and the investment firm of Mark Zuckerberg and Henry Kravis.