Amazon CEO Jeff Bezos' fortune grew by $13.5 billion in just 15 minutes on Thursday.

Bezos' windfall came after Amazon's stock price increased by 12% to $12,000 during trading Thursday in New York.

The bulk of Bezos' $116 billion fortune comes from his Amazon stock, with ventures such as Blue Origin and the Washington Post newspaper comprising the rest.

Thursday's stock surge came after a stellar quarter for Amazon, as it posted revenues of $87 billion for the fourth quarter of 2019 – up from $72.4 billion in Q4 2018.

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Jeff Bezos may have been the only ultra-wealthy billionaire who failed to get richer in 2019, but he's making up for it in 2020.

The Amazon CEO's fortune grew by $13.5 billion in just 15 minutes on Thursday, as first noted by Bloomberg.

Bezos' windfall came after Amazon's shares surged around 12% to $2,100 during after-hours trading Thursday in New York.

The bulk of the 56-year-old's fortune comes from his ownership of roughly 12% of Amazon's stock.

The rise in his stock's value would put his current net worth at about $129 billion, boosting him above Microsoft founder Bill Gates. The two have traded the spot of the wealthiest person in the world over the last year.

Bezos is a keen investor, operating through his eponymous VC vehicle Bezos Expeditions. His panoply of ventures – including his ownership of aerospace firm Blue Origin and the Washington Post newspaper – supplies the rest of his wealth.

Amazon's gamble on providing faster shipping for Prime customers looks to have paid off – for both the company and Bezos himself. Amazon

He has also been recognized as the richest person in modern history after his fortune hit the $150 billion mark in July 2018.

Thursday's stock surge came after a stellar quarter for Amazon.

The tech giant reported earnings per share of $6.47, versus expectations of $4.04.

Its gamble on making one-day shipping the default for Amazon Prime members looks to have paid off, as it posted revenue of $87 billion for the fourth quarter of 2019 – up from $72.4 billion the prior year.