Wall Street was slightly higher in volatile trading on Thursday as a decline in biotech stocks offset gains in energy shares.

The Nasdaq biotech sector was down 3.5 percent, with Celgene’s 4.8 percent fall weighing the most.

Incyte’s 11 percent drop also dragged the index lower, after the company said it would stop a mid-stage study on a key cancer treatment.

Crude rose as much as 6 percent earlier on speculation that Saudi Arabia and other OPEC countries would cut output to boost prices. [O/R]

“Oil’s been firmly in control of the market,” said Kim Forrest, senior equity research analyst at Fort Pitt Capital Group in Pittsburgh.

“I think what oil has become is a proxy for ‘are we going into a recession?’,” she said.

At 11:05 a.m. ET (1605 GMT), the Dow Jones industrial average was up 33.83 points, or 0.21 percent, at 15,978.29, the S&P 500 was up 7.47 points, or 0.4 percent, at 1,890.42 and the Nasdaq Composite index was up 34.00 points, or 0.76 percent, at 4,502.17.

Six of the 10 major S&P sectors were lower, led by the 2.15 percent fall in health stocks.

Abbott Labs was down 8.8 percent at $36.94 after it reported a drop in revenue. The stock was the biggest drag on the healthcare sector.

Facebook surged 12.2 percent to $106.23 after the world’s biggest social network reported a 52 percent jump in revenue.

The U.S. Federal Reserve kept interest rates unchanged on Wednesday and said it was “closely monitoring” global economic and financial developments, while keeping an optimistic view of the U.S. economy.

Advancing issues outnumbered decliners on the NYSE by 2,081 to 847. On the Nasdaq, 1,582 issues rose and 993 fell.

The S&P 500 index showed four new 52-week highs and 20 new lows, while the Nasdaq recorded 12 new highs and 115 new lows.

(Reporting by Abhiram Nandakumar in Bengaluru; Editing by Anil D’Silva)