SAN FRANCISCO — Tesla CEO Elon Musk became the world’s richest person on Thursday, surpassing Amazon chief executive Jeff Bezos after an early-morning stock rally.

Bloomberg’s Billionaires Index estimated Musk’s net worth at $181 billion on Wednesday, about $3 billion behind Bezos. That was before a nearly eight percent stock rally Thursday by Tesla, strongly outpacing Amazon’s gains for the day and vaulting Musk to the rank of world’s richest. The wealth estimates are largely based on Musk and Bezos’ stock holdings in Tesla and Amazon, respectively.

“How strange,” Musk tweeted, responding to a tweet about the news. “Well, back to work ...,” he added.

(Bezos owns The Washington Post.)

The title of world’s richest caps an extraordinary run for Musk and Tesla, especially during a pandemic that has ground the world’s economy to a halt, with record lines outside food banks and elevated unemployment. Musk was criticized for repeated attempts to keep Tesla’s plant open and then for bringing workers back onto the line as covid-19 raged, and cases were even reported inside Tesla’s facilities.

It marks an unlikely turnaround for Musk. Just 18 months ago, Tesla’s stock appeared to have bottomed out on the heels of legal and regulatory fears, as well as concerns about Musk’s leadership. Musk famously tweeted he had “funding secured” to take Tesla private in August 2018, which kicked off a slew of regulatory battles and plunged Musk’s status as CEO into question. By 2019 Tesla faced concerns over demand, mounting losses and a shortage of cash — and its stock dropped to a near-term low around June 2019.

But last year, the stock rose steadily — then meteorically — as the company posted consecutive quarters of profits and appeared to prove the viability and demand for electric cars.

Analysts warned the stock could be valued too highly as Tesla took the title of the world’s most valuable automotive company. Musk himself even sent the stock down in May when he posted a tweet saying the stock was “too high imo,” using shorthand for “in my opinion.”

Musk‘s success hasn’t been limited to earth. In May he oversaw the successful launch of a pair of NASA astronauts into space with his other company, the aerospace outfit SpaceX. They returned safely two months later. It was a landmark achievement for the company that aimed to show rockets could be deployed and reused, demonstrating the viability of a new era of space travel with the ultimate goal of flying humans to Mars.

Musk made his fortune early on with PayPal, which he co-founded and pocketed $165 million in its sale to eBay. He invested in Tesla in 2004, a year after its founding, and maintains around a 20 percent stake in the company, according to Forbes. He was named the company’s chairman in 2004, a title he lost in the wake of his “funding secured” fiasco in 2018. He became CEO in 2008, a title he retains to this day.

Musk founded SpaceX two decades ago, setting his sights on Mars and aiming to disrupt an industry deeply entrenched in the government with a private venture focused on human spaceflight.

Musk’s rapid ascent through the charts illustrates a wealth gain of historic proportions. The Washington Post reported Musk’s wealth stood at $37 billion in 2020. That means Musk added at least $148 billion more to his personal fortune over the span of a year.

The growth in Musk’s portfolio over the span of a year is more than the entire net worth of the world’s third richest person, Bill Gates, according to Bloomberg’s figures: $132 billion.

Musk surpassed Jeff Bezos, whose wealth is largely composed of his stock in the e-commerce giant Amazon, which he founded and where he remains chief executive.

Amazon has grown into the third largest publicly traded company in the world behind Apple and Microsoft, as measured by market capitalization, which currently is $1.6 trillion.

Bezos and his wife MacKenzie Scott divorced in 2019, after details of his extramarital affair emerged.

In the divorce settlement, though, Bezos retained 75 percent of his Amazon stake as well as all of the couple’s joint holdings in The Post, which he bought in 2013, and the space flight company, Blue Origin.

Jay Greene contributed to this report.