Bill Gates was once the richest man in the world for 18 years, and currently boasts a jealousy-inducing net worth of $124 billion from cofounding the software titan Microsoft. But now his former right-hand man has more money in his bank account than he does, thanks to Gates’ billion-dollar philanthropic spending.

On July 3 last week, Gates was standing on a fortune of $175 billion, ranked as the fifth-wealthiest person alive on the Bloomberg Billionaire Index. But his wealth plummeted over the span of the next couple of days as $51 billion was drained from his net worth, shooting him down the list to 12th place right below fellow tech pioneer Michael Dell.

Gates’ wealth disappeared so rapidly as the index readjusted for the 69-year-old technology mogul’s philanthropic efforts. Bloomberg noted that the appreciation rates were lowered last week to “better reflect Gates’ outside charitable giving and the wealth estimate,” based on a May 8 blog post from the former Microsoft CEO.

The note disclosed that Gates would be donating his vast fortune to charity much faster than previously planned; Over the next 20 years, he would donate almost all of his wealth to the Gates Foundation that he spearheaded with ex-wife Melinda French Gates, which will close by the end of 2045.

“People will say a lot of things about me when I die, but I am determined that ‘he died rich’ will not be one of them,” Gates wrote. “There are too many urgent problems to solve for me to hold onto resources that could be used to help people.”

Gates has been determined to whittle down his wealth for the greater good for years, even saying that his children would inherit “less than 1%” of his fortune. And now, his goal is being reflected in his net worth. His charitable giving even cleared the way for his former No. 2 from the Microsoft days, Steve Ballmer, to take his spot in fifth with $172 billion to his name—and it’s not the first time it’s happened.

Fortune reached out to Gates for comment.

Who is Steve Ballmer—and why is he richer than Gates?
Most employees never expect to earn more than their bosses. But Ballmer got his foot in the door at a lucky time, and for decades since, money has been percolating into his bank account.

Microsoft was in its early days when Ballmer joined as an assistant to the president in 1980—he was the 30th employee to join the growing technology company and effectively functioned as a business manager. He had dropped out of Stanford’s MBA program to take the job, and was offered a $50,000 base salary alongside 10% of any profit growth he generated at the business. Ballmer didn’t get a single share at the time, but the 10% cut proved to be extremely lucrative.

But soon the business was growing so quickly that the portion wasn’t financially feasible, so in renegotiations, Ballmer traded his profit-sharing deal for an 8% stake in the company. The company’s cofounder Paul Allen wasn’t thrilled with the trade-off, arguing it was still too large of a share for Ballmer. But Gates put his own money on the line to fulfil Ballmer’s request—and the rest is history.

The former assistant to Gates eventually rose up the ranks and took his boss’s role, serving as CEO of the company from 2000 to 2014. He held 333 million shares in Microsoft, or around a 4% stake worth $22.5 billion, when he stepped down as chief executive. Today, most of the 69-year-old’s investment portfolio is still wrapped up in the business’s stock—but he attributes his vast wealth to being in the right place, at the right time and not cashing in too early.

“If there’s anybody that will tell you all their success is because they were a genius, I’d say they should go look for the luck,” he told the Wall Street Journal last year. “Forget the stock price. I had luck, essentially, in getting to listen to the right people. But I also had luck in terms of my loyalty to the company and not wanting to be a seller as a leader of the business.”

Ballmer has since ventured into other arenas outside of tech. The baby boomer bought the Los Angeles Clippers for $2 billion the same year he retired from Microsoft, and the team is now valued at $5.5 billion.

Following in Gates’ footsteps, he also has a soft spot for charity; he’s donated more than $4 billion of his fortune so far, and founded philanthropic organization Ballmer Group focused on improving economic mobility for families in the United States.