The world’s 400 richest people lost $182 billion this week from their collective fortunes as weak manufacturing data from China and a rout in commodities sent global markets plunging.

The weekly drop for the Bloomberg Billionaires Index, a group that includes Warren Buffett and Glencore Plc’s Ivan Glasenberg, was the biggest since tracking of the expanded list began in September 2014.

The combined net worth of the index members fell by $76 billion on Friday alone, when the Standard & Poor’s 500 Index of U.S. stocks ended its worst week since 2011.

“For them that’s a fractional percentage, even though $182 billion is a big number,” said John Collins, director of investment advisory at Aspiriant, which oversees more than $8 billion for high net worth clients.

“A week like this feels really bad, but when you take a step back, in a big picture view it’s not a disaster by any means.”

Friday’s losses put the world’s richest 400 into the red for the year to date. They’re now down $74 billion in 2015, with a collective net worth of $3.98 trillion.

The week’s largest setback in dollar terms was experienced by Buffett, who saw his fortune drop by $3.6 billion as Berkshire Hathaway Inc. slipped more than 5 percent. The investor is the world’s third-wealthiest person, with a fortune of $63.4 billion, according to data compiled by Bloomberg.

The slump in oil, which had its longest weekly losing streak since 1986 amid signs of an extended supply glut, contributed to $15.2 billion in losses for the world’s wealthiest energy billionaires. Continental Resources Inc. Chairman Harold Hamm saw $895 million, or 9 percent of his net worth, vanish this week.

Glencore’s Glasenberg

Glasenberg, chief executive officer of mining company Glencore Plc, lost $237 million during the week as commodity prices slid to their lowest levels in 13 years.

Glencore reached a record low in London on Friday, down more than 8 percent from a week earlier, after the trading house reported its profit sank 56 percent in the first half of the year. Glasenberg’s fortune has decreased more than 40 percent in 2015, to $3.1 billion.

China’s 26 wealthiest people, pummeled by Hong Kong’s bear market and a weaker yen, lost $18.8 billion during the week. Wang Jianlin of Dalian Wanda Commercial Properties Co. was hit hardest, losing $3.5 billion.

Eleven billionaires added to their fortunes in spite of the market turmoil. The week’s biggest dollar gainer was Sun Pharmaceuticals’ Dilip Shanghvi. The world’s 39th-richest person became $467 million wealthier, elevating his net worth to $18.9 billion.

The Bloomberg Billionaires Index takes measure of the world’s wealthiest people based on market and economic changes and Bloomberg News reporting. Each net-worth figure is updated every business day at 5:30 p.m. in New York and listed in U.S. dollars.