Carlos Slim loses $6.7 billion in a week

Carlos Slim, the world's richest man, lost around $6.7 billion last week.

According to data compiled by Bloomberg, Slim's stock portfolio has fallen 9.5 percent since July 29 when measured in U.S. dollars, and is now valued at $64.4 billion. The Standard & Poor’s 500 has fallen 7.2 percent during that time.

Slim, 71, has taken a hit as Mexico’s benchmark IPC index dropped 6.4 percent and the peso slid 2.3 percent against the dollar on concerns that the flagging U.S. economy will hurt demand for assets in its southern neighbor. The removal of three of Slim’s companies from the IPC index has made matters worse for the billionaire.

Leon Cabrera, a trader at Mexico City-based Vanguardia Casa de Bolsa, told Bloomberg that Slim was "particularly hurt" by the companies that were removed from the IPC.

When Slim's holding are measured in Mexican pesos, the drop in value was somewhere around 7.3 percent.

Forbes named Slim the world's richest man, and put him at the top of its annual World Billionaires’ list, for the second year in a row this year. In March, the magazine put Slim's net worth at $74 billion, and said it had grown by $20.5 billion in the previous year, on the strength of the Mexican stock market, a stronger peso, and "successful mining and real estate spinoffs from conglomerate Grupo Carso."

According to Bloomberg, Slim's fellow billionaires Bill Gates and Warren Buffett have fared slightly better during the recent market turmoil. Gates’s Microsoft Corp. dropped 6.3 percent last week, while Buffett’s Berkshire Hathaway Inc. fell 3.9 percent.

World markets are expected to open down on Monday, in the wake of Standard & Poor's decision to downgrade the U.S. credit rating from AAA to AA+. Wall Street experienced its worst week since September 2008 last week, and Reuters reports that global stocks lost $2.5 trillion in value.