Billionaire investor Carl Icahn withdrew his $29-a-share offer to buy the remaining stake in CVR Energy Inc., saying it isn’t “feasible at this time.”

Icahn, who owns about 82 percent of the oil refiner, said on Aug. 6 he would be willing to pay as much as $30 a share for the company.

“Since then a number of market conditions have changed, including a significant widening of crack spreads,” Icahn wrote in a letter to the Sugar Land, Texas-based company’s board Tuesday.