The net worth of billionaire Saudi prince Alwaleed bin Talal Al Saud—who was detained by the Saudi government on Saturday as part of what officials have called an anti-corruption campaign—is continuing to fall dramatically.

Alwaleed’s fortune dropped $855 million on Tuesday as the share price of his holding company, Kingdom Holding—which trades on Saudi Arabia’s Tadawul exchange—continued to drop. The stock, which now comprises half of his net worth, is down 21% since the end of normal trading on Thursday, November 2. (The Tadawul is closed on Fridays and Saturdays.) Alwaleed owns 95% of Kingdom Holding; the remaining 5% trades on the Saudi stock exchange.

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In all, Alwaleed’s net worth is down $2.8 billion since Saturday evening. He is now worth an estimated $15.9 billion, according to Forbes’ real-time rankings of the world’s billionaires. He is presently the 83rd richest person on the planet; he was ranked 64th on Saturday.

Alwaleed, 62, is the nephew of Saudi king Salman bin Abdulaziz Al Saud and is a cousin of the country’s crown prince, Mohammed bin Salman. He was one of more than a dozen individuals reportedly arrested last weekend in what many news outlets have described as a purge designed to consolidate the crown prince’s power.

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Forbes profiled Alwaleed in a 2013 story that documented his wild eccentricity and self-promotional tendencies. The billionaire had once lived a quieter life. He attended Menlo College in California and Syracuse University before launching Kingdom Holding in 1980. He is perhaps best known in the West for his investments in high-profile companies, including Lyft and Twitter.

Contacted by Forbes on Monday, Kingdom Holding did not respond to a request for comment. – Written by