The S&P fell 0.9% to 4,124.99 in Wednesday midday trading.
The Dow 30 was down 0.7% to 32,938.52 and Nasdaq was off 0.5% to 12,111.65.
Crude oil jumped 2.2% to $122.06 a barrel.
Gold rose 0.4% to $1,860 an ounce.
The yield on a 10-year Treasury bond increased 1.3% to 3.009%.
Staar Surgical Co. (Nasdaq: STAA) increased 5.6% to $73.12 with a $3.5 billion market cap, The company yesterday announced more than two million of its Visian Implantable Collamer lenses have been sold globally. Shares for the Lake Forest-based medical eye lens developer are up more than 11% in the past week.
The Ensign Group Inc. (Nasdaq: ENSG) fell 4.5% to $76.28 per share and a $4.2 billion market cap. Shares for the San Juan Capistrano nursing home owner-operator are trading at almost 25% of their daily average, and are down about 11% year-to-date.