Life Time Fitness CEO Bahram Akradi has upped his ownership stake in Northern Oil and Gas to nearly 10 percent, and the newfound activist investor is aiming for a seat on the company’s board.

Northern Oil and Gas this week essentially replied with a thanks-but-no-thanks, but Akradi said in an interview Friday that he’ll continue his quest. “I intend to get on the board and make the necessary moves to make the company as successful as it should be,” he told the Star Tribune.

Akradi, Northern Oil’s second largest investor, said he will be looking for the support of other shareholders to call a special meeting to change the composition of the board. “At this time, however, I want to be clear I’m not acting as a group with any other shareholders.”

Northern Oil didn’t return a call for comment.

Akradi revealed in October that he had built a 5.3 percent stake in Northern Oil, which invests in oil leases and drilling projects in North Dakota. He noted at the time in a federal securities filing that he would be an activist investor and engage in discussions with management.

Akradi built Chanhassen-based Life Time Fitness into one of the nation’s largest fitness center operators. He hasn’t been an activist investor, though Life Time itself came under pressure from activist investors a few years ago. They wanted the then publicly traded Life Time to spin off its real estate assets. Akradi led a buyout to take the company private in 2015.

Akradi’s stake in Northern Oil has grown to 9.7 percent as he scooped up about 2 million shares between April 17 and May 31, according to a June 7 filing with the U.S. Securities and Exchange Commission. The filing included a letter from Akradi to Northern Oil Chairman Richard Weber regarding — among other things — Akradi’s request for a seat on Northern Oil’s board.

Weber replied Tuesday, thanking Akradi for his interest, but adding the “board has determined that it is not appropriate to increase its size at this time,” according to an SEC filing. Northern Oil noted that it has added two new directors over the past year.

The directors, Michael Frantz and Michael Popejoy, are affiliated with TRT Holdings, a Dallas-based company with a 19.7 percent stake in Northern Oil. TRT, an affiliate of billionaire Texas oilman and hotel magnate Bob Rowling, is Northern Oil’s largest shareholder.

One of those TRT directors on Northern Oil’s six-member board is essentially a replacement for Michael Reger, Northern Oil’s former CEO and co-founder. Reger was fired in August after he told the board that securities regulators might be pursuing an enforcement action against him. Later, Reger settled claims against him by the SEC for $8 million. He’s suing Northern Oil for wrongful termination while the company is being run by an interim CEO.

In addition to management turmoil, Northern Oil’s fortunes plummeted with the oil bust that began in earnest in 2015. The company posted more than $1 billion in net losses in 2015 and 2016, though it turned a $17 million profit during 2017’s first quarter. Northern Oil’s stock, which has traded between $1.55 and $5 over the past year, closed Friday at $1.65.

In a letter to Northern Oil earlier this month, Akradi urged the company’s board to form a “strategy committee charged with clearly defining the company’s direction.” Amplifying on his written comments, Akradi said in an interview that Northern Oil should be a consolidator in that region.

He also said “the company needs to do a better job of explaining the value of their stock.” In his letter to Northern Oil’s Weber, he said the board lacks “transparency.”

Weber, in a written response to Akradi, said Northern Oil was “dedicated” to taking advantage of growth opportunities that are “beginning to emerge from the worst commodity price correction in recent memory.”