New York-based Jana Partners said it had a 7.5% stake in QEP Resources Inc. The hedge fund bought 15.5 million shares which included options in the oil and natural gas producer. According to a regulatory filing, Denver-based QEP was the worst oil and natural gas company performer this year.

Barry Rosenstein of Jana Partners said he had already talked with QEP about separating the company's midstream gas processing unit into a standalone business. Jana also said they had discussed with QEP about making changes to the company's compensation practices as well as adding to its directors.

In a letter to the board of directors of QEP, Rosenstein said "We have attempted to work constructively to help refine the company's strategic direction and to address the company's consistent share price underperformance." However, he said the executives of the firm did not realize the value of the midstream business. He added that the company had snubbed the hedge fund's offer to help.