The Richest Man You've Never Heard of Isn't Sure What to Do With His Billions Autry Stephens' net worth has grown by $17.5 billion since February last year, behind only Nvidia's Jensen Huang and Meta's Mark Zuckerberg.

^{This article originally appeared on Business Insider.}

An 85-year-old oil tycoon is cashing out — but he appeared solemn in an interview about selling his business.

Autry Stephens sold his company, Endeavor Energy Resources, to Diamondback Energy earlier this week. The $26 billion cash-and-stock deal would make him the richest oil tycoon in the US, Bloomberg reported.

But the taciturn Stephens appeared reluctant to leave the company he founded in 1979, telling The Wall Street Journal he made the decision largely because of a cancer diagnosis.

"I'll miss the people there," he told the Journal in a recent interview. "It was kind of a little family."

Stephens had long resisted outside efforts to buy Endeavor, which was one of the last independent major oil companies in the rich Permian Basin of western Texas. But that changed when he was diagnosed with prostate cancer, he told the Journal.

He said he decided against passing the company on to his daughter, Lyndal Greth, who sits on the company's board and has children of her own, and that his son wasn't part of the family business.

Now, the deal with Diamondback Energy — which beat out other big-name bidders such as ExxonMobil and ConocoPhillips — is poised to make the company a powerful force in the domestic energy scene.

Stephens is well known for his unassuming style. He drove an old-model Toyota Land Cruiser to work and flew budget on Southwest Airlines, the Journal reported. That reflects his modest upbringing on a farm in central Texas that grew peanuts and watermelons, according to his University of Texas Austin alumni profile.

Despite his massive fortune and brush with fame — he was featured on the truTV reality series "Black Gold" — his career trajectory seemed to remain focused on his initial ambitions, which he said were "to earn a steady paycheck and comfortable retirement," according to UT Austin.

Stephens has credited his success to his openness to new ideas and technologies, as well as a cash-first drilling strategy that Bloomberg reported helped him survive the 2008 financial crisis while many other US operators went under.

"The history of the oil industry is full of stories of people making and losing fortunes several times over," he told his alma mater.

Asked by the Journal what he would do with his newfound billions, Stephens said that he hadn't really thought about it yet.

The Endeavor sale has since catapulted Stephens from 130th to 77th on Bloomberg's Billionaires Index. His net worth has grown by $17.5 billion since this time last year, behind only Nvidia's Jensen Huang and Meta's Mark Zuckerberg.