A majority of CVR Energy Inc. shareholders threw their support behind a takeover offer from billionaire investor Carl Icahn, giving him the mandate needed to proceed with his planned shakeup of the petroleum refining and marketing company.

Icahn, who is one of the company's largest shareholders, in February launched a tender offer for CVR worth $30 a share plus a contingent value right.

The activist investor scored a win in the heated battle last month when a majority of the company's outstanding shares were tendered in support of his offer.

The show of shareholder support prompted the CVR board to strike an agreement with Icahn that lifted a so-called "poison pill" blocking hostile takeovers and allowed him to push ahead with his bid.

As of Friday night, roughly 63% of CVR shares unaffiliated with Icahn had been tendered in support of the bid, giving him majority ownership of the company.

Per his agreement with the company, seven members of its nine-member board will be replaced automatically with seven individuals nominated by Icahn.

In addition, he is commencing a subsequent offering period for shares that haven't already been tendered. That offer will expire at 11:59 p.m. EDT on May 18.

"We are pleased with the results of our tender offer and are excited to have CVR join the Icahn Enterprises family," Icahn said Monday. "We look forward to working together with the CVR team."

A spokeswoman for the company wasn't immediately available for comment.

Shares of CVR closed Friday at $30.05 and were inactive premarket. The stock has surged 60% since the start of the year.