When Steve Ballmer joined Microsoft he didn’t get a single company share. But now, his skyrocketing Microsoft holdings have made him richer than the company’s founder.

The 68-year-old former Microsoft CEO squeaked by his onetime boss Bill Gates to become the sixth richest person in the world on Monday with a net worth of $157 billion. He is now richer than many well-known tech entrepreneurs including Google cofounder Sergey Brin, Oracle founder Larry Ellison, and Dell Technologies CEO Michael Dell.

It’s also the first time that Ballmer’s net worth has surpassed that of Gates, and one of the few times in history an employee has come to be richer than a company’s founder. Ballmer is the only person with a net worth of $100 billion or more who made their money as an employee rather than a founder, as Fortune previously reported.

Ballmer’s net worth was boosted by a rally in Microsoft’s shares, which closed at an all-time high on Tuesday and have surged 22% since January. Shares of the company represent about 90% of his net worth, according to the Bloomberg Billionaires Index, and Microsoft has been one of the biggest beneficiaries of the AI boom fueling markets, thanks to its $10 billion investment in OpenAI.

In 2014, Ballmer left Microsoft with about a 4% stake worth $22.5 billion, according to Forbes. At the time, he said that he was holding on to his shares for the long term, Forbes reported.

“I’d like to own Microsoft shares until I either give something to charity or I die,” he told the outlet.

Meanwhile, Gates has diversified his portfolio over the years away from the company he founded, with half of his holdings now managed through private investment firm Cascade Investment. He has a $21 billion stake in waste management company Republic Services through Cascade, Bloomberg reported.

Giving away money

Gates’ major philanthropic donations also factor in. As of 2023, Gates and his ex-wife Melinda French Gates had donated $59.5 billion to the Bill & Melinda Gates Foundation, turning it into the one of the world’s largest charitable foundations. In 2010, Gates also cocreated the Giving Pledge with French Gates and investor Warren Buffett, and has promised to give away most of his wealth during his lifetime.

Although Steve Ballmer’s holdings have made him one of the richest men in the world, when he joined as the company’s 30th employee in 1980, he didn’t get a single share. After dropping out of Stanford Business School, he served as a quasi–personal assistant to Bill Gates with the unimpressive title “business manager,” Forbes reported.

Yet, because Microsoft was looking to grow rapidly at the time, Gates and his cofounder, Paul Allen, agreed to give Ballmer 10% of the profit growth he generated on top of his $50,000 yearly salary.

That deal turned out to be key to Ballmer’s future wealth. Soon, Microsoft was growing so fast that Ballmer’s 10% cut no longer made sense financially for the company. When Microsoft reorganized as a corporation, Ballmer negotiated an 8% slice for himself in exchange for giving up his profit-sharing deal, while Gates and Allen kept 84% and another 8% was designated for other employees, Forbes reported. Although Allen was opposed to giving Ballmer such a large stake, Gates stepped in and said Ballmer’s 8% cut could be funded by a drawdown of his own holdings, according to Forbes.

While at the time Gates put his own money on the line for Ballmer, the two have since drifted apart.

“Microsoft was kind of the thing that really bound us,” Ballmer told Bloomberg Television in 2016. “We started off as friends, but then really got quite enmeshed around Microsoft. Since I’ve gone, we really have drifted a little bit.”