Oracle founder Larry Ellison has overtaken Tesla chief Elon Musk as the world’s richest person, after an unprecedented surge in Oracle’s share price added more than $100 billion to his fortune in a single day.

According to the Bloomberg Billionaires Index, Ellison’s net worth reached $393 billion on Wednesday morning, surpassing Musk’s $385 billion. The 81-year-old Ellison, who has spent more than five decades building Oracle into one of the world’s most important software companies, now claims the top spot on the global rich list for the first time.

Oracle shares soared as much as 41% on Wednesday to an all-time high of $338, marking the company’s biggest-ever single-day jump. Ellison, who owns around 1.16 billion shares, saw his personal wealth balloon by $101 billion — the largest one-day increase in the index’s history.

The rally was sparked by Oracle’s bullish forecast for its cloud computing business, which is emerging as a key player in the race to dominate artificial intelligence infrastructure. Oracle CEO Safra Catz revealed on an analyst call Tuesday that the company had secured four multi-billion-dollar contracts with three separate clients in the fiscal first quarter. That pushed total bookings to $455 billion, quadruple the level from a year earlier.

Catz added that Oracle expects revenue from its Oracle Cloud Infrastructure division to climb 77% year-on-year to $18 billion, with ambitions to hit $144 billion by 2030. The projections stunned Wall Street and thrust Oracle into the same competitive league as Amazon, Microsoft, and Google in the cloud wars.

For Ellison, the historic milestone caps decades of growth since co-founding Oracle in 1977. The company’s focus on databases and enterprise software made it a backbone of the corporate IT world, but its pivot to cloud services has been the driver of this latest surge.

Meanwhile, Musk’s wealth has been sliding as Tesla shares — the mainstay of his fortune — are down 12% so far this year. On Tuesday alone, Musk’s net worth fell nearly $49 billion, highlighting the volatility that comes with his heavy reliance on Tesla’s performance.