Inc.’s weaker-than-expected second-quarter results has sent its founder’s fortune tumbling.

The net worth of Jeff Bezos fell US$13.5 billion after Thursday’s after-market results missed Wall Street’s expectations and foreshadowed an end to the retailer’s pandemic-fueled sales surge. The drop erased 80 per cent of his wealth gains for the year.

Amazon’s shares dropped 7.2 per cent to US$3,339.18 at 9:53 a.m. in New York, lowering the company’s ex-chief executive officer’s fortune to US$193.6 billion. He still remains the world’s richest person, according to the Bloomberg Billionaires Index, some US$8 billion ahead of Tesla Inc.’s Elon Musk.

It’s been a mixed week for America’s richest tech billionaires. While Google-parent Alphabet Inc.’s rosy earnings boosted the net worth of co-founders Sergey Brin and Larry Page, strong results from Microsoft Corp. and Facebook Inc. didn’t translate into a wealth-bump for their billionaire shareholders.

Mark Zuckerberg, who spent the week touting his vision of Facebook’s future as an all-encompassing “metaverse,” lost US$5.4 billion Thursday as the social networking company’s shares fell the most in two months over concern about growth in advertising sales.