A 4.8% rally in the electric carmaker’s share price Thursday boosted Musk past Amazon.com Inc. founder Jeff Bezos on the Bloomberg Billionaires Index, a ranking of the world’s 500 wealthiest people.

The South Africa-born engineer’s net worth was $188.5 billion at 10:15 a.m. in New York, $1.5 billion more than Bezos, who has held the top spot since October 2017. As chief executive officer of Space Exploration Technologies Corp., or SpaceX, Musk is also a rival to Bezos, owner of Blue Origin LLC, in the private space race.

The milestone caps an extraordinary 12 months for Musk. Over the past year his net worth soared by more than $150 billion in possibly the fastest bout of wealth creation in history. Fueling his rise was an unprecedented rally in Tesla’s share price, which surged 743% last year on the back of consistent profits, inclusion in the S&P 500 Index and enthusiasm from Wall Street and retail investors alike.

Bezos would still hold a wide lead over Musk had it not been for his divorce, which saw him cede about a quarter of his Amazon stake to his ex-wife, MacKenzie Scott, and his philanthropy. He donated shares worth about $680 million in November.