Healthcare stocks were jumping on the upside and the down side midday.
Drug stocks were among the biggest gainers and losers following quarterly results, which left the S&P 500 Health Care Sector index near the unchanged level. It was up about 0.05% as of 11:45 AM ET (15:45 GMT).
Mallinckrodt (NYSE:MNK) soared about 24% on strong earnings and a boost in guidance. The company results were buoyed by stronger-than-expected sales of its H.P. Achtar Gel, which treats multiple sclerosis and other conditions.
But that treatment is not without its controversy. It now costs $38,000 a year compared with its original price of $40.
On the flip side, Spark Therapeutics (NASDAQ:ONCE) plunged into the red, falling about 30%.
The company reported adverse reactions in two patients in a trial for a hemophilia treatment.
And dental supply company Dentsply Sirona (NASDAQ:XRAY) lost about 19% after cutting its full-year outlook.
Energy stocks were active again as crude oil rose on the first day that the initial round of U.S. sanctions on Iran went into effect.
The S&P Energy Sector index was up about 1%. Components ConocoPhillips (NYSE:COP), Newfield Exploration (NYSE:NFX) and Marathon Petroleum (NYSE:MPC) all gained more than 2%.