SandRidge Energy Inc. (SD) founder Tom Ward was ousted as the oil and gas producer's chief executive and chairman, and will take one of the biggest severance packages seen in the energy industry--about $90 million, the company said Wednesday.

Mr. Ward came under fire last year for his high pay, the company's weak stock performance and its dealings with businesses controlled by Mr. Ward and his family during a monthslong proxy fight. A spokesman said he was unavailable to comment.

Mr. Ward's ouster wasn't unexpected. SandRidge in March settled a proxy fight with activist shareholder TPG-Axon Capital LP, agreeing to either fire Mr. Ward or give control of its board to the hedge fund. SandRidge, with a stock-market value of about $2.4 billion, appointed four directors nominated by TPG-Axon at the time.

SandRidge promoted Chief Financial Officer James Bennett to CEO. Mr. Bennett, who will remain president, worked in private equity prior to joining SandRidge in 2011.

Mr. Ward founded SandRidge in 2006, after leaving natural-gas producer Chesapeake Energy Corp., which he had co-founded with Aubrey McClendon in 1989. Both executives in the past year came under pressure for their companies' heavy spending, and controversies involving their mixing of personal finances with the companies they ran. Mr. McClendon, who resigned from Chesapeake in April, received a package valued at nearly $50 million, including $11 million in cash to be paid in regular installments.

TPG-Axon and another large shareholder, Mount Kellett Capital Management LP, questioned SandRidge's transactions with entities controlled by Mr. Ward and his family. SandRidge has said reviews of the matter by its board and an outside law firm didn't find any misconduct by Mr. Ward.

Mr. Ward's termination has been deemed "without cause," which allows him to take the exit package outlined in his employment agreement.

"Two separate Board investigations have now confirmed that Tom Ward's actions were proper. No one has worked harder for or been more loyal to SandRidge Energy than Mr. Ward," said Steven M. Bauer, a lawyer representing Mr. Ward.

Mr. Ward's ouster comes amid a rise in activism in the energy patch, as dissident shareholders also have shaken up the leadership of energy producer Hess Corp. and offshore oil driller Transocean Ltd.

TPG-Axon took aim at SandRidge in November, demanding Mr. Ward step down for his role in land leases that were sold by Mr. Ward's family members to SandRidge and the company's poor stock performance. "The board has sanctioned compensation levels for Tom Ward that are unconscionable in light of company performance," the shareholder wrote last November. A spokesman for TPG-Axon declined to comment on Wednesday.

SandRidge said its board terminated Mr. Ward after reviewing the findings from an independent investigation into allegations of improper related-party transactions leveled against Mr. Ward during the proxy fight. The allegations involved drilling leases that were sold by Mr. Ward's family members to SandRidge.

Board members, however, decided the investigation's findings didn't merit Mr. Ward's termination with cause, which would have limited the value of his exit package, and that the termination was based on the "decision that new leadership is desirable at this time."

Interim nonexecutive Chairman Jeffrey Serota said in an interview Wednesday that the investigation was "exhaustive" and that "no stone was left unturned." Regarding Mr. Ward's exit package, Mr. Serota said, "It's all in his employment agreement; there was no negotiation."

"The challenges and noise that we went through are all settled now," Mr. Serota said. "It's about looking forward and executing on our business plan."

Under terms of his employment contract, Mr. Ward will receive a lump sum cash payment of $53.5 million; see 6,331,475 shares of previously granted restricted stock vest, which is worth about $32.1 million based on Wednesday's closing price of $5.08; and his base salary of $1.5 million a year for three more years.

Its shares gained 4% in after-hours after finishing up 11 cents, or 2%, at $5.08 on the New York Stock Exchange.

Alison Sider contributed to this article.

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