Mark Zuckerberg’s fortune slid US$4 billion Thursday as shares of his Facebook Inc. dropped 5.7 per cent, a day after the social-media giant posted its slowest-ever quarterly sales growth.

The decline left the chief executive officer with an US$81 billion fortune as of 10:07 a.m in New York, with the shares trading at US$210.41 apiece. Zuckerberg, 35, remains the world’s fifth-richest person, according to the Bloomberg Billionaires Index. The ranking officially updates after the close of each trading day in the U.S.

Despite the drop, Zuckerberg’s net worth is still up this year. His fortune had climbed US$6.6 billion through Wednesday.

Shares of Menlo Park, California-based Facebook had dropped as much as 8.3 per cent Thursday before paring the decline.

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