After Amazon.com's results left investors disappointed, Jeff Bezos lost $20.5 billion of his fortune.
The company's shares were down after it reported a quarterly loss and slower sales growth. The net worth of Bezos fell from a peak this year of more than $210 billion.
The 500 richest people in the world lost more than $50 billion on Friday. The benchmark S&P 500 Index fell 3.6% and the tech-laden Nasdaq 100 Index slid 4.5%, closing out their worst month since 2008.
The world's richest person after Musk, Bezos, has lost nearly $44 billion of his wealth this year.
Amazon has higher labor costs due to a hiring binge during the Pandemic and a surge in inflation that may hold back sales.
The company had a net loss of $3.8 billion in the quarter ended March 31, compared with a profit of $8.1 billion in the same period last year.