David Einhorn, who runs hedge fund Greenlight Capital, criticized Pioneer Natural Resources Co. for spending too much money without returns and called it the “motherfracker.”

“We think Pioneer generates a negative equity returns on capex” he said at the Sohn Investment Conference in New York on Monday. Pioneer shares fell 2.6 percent to $167.13 at 12:23 p.m. in New York.

Einhorn spoke negatively about fracking companies and listed several in his slide presentation, including Concho Resources Inc., EOG Resources Inc., Whiting Petroleum Corp. and Continental Resources Inc.

“None of them generated excess cash flow, even when oil was at $100 a barrel,” he said about the industry as a whole.