CNBC's Kate Kelly reports that hedge fund titan Bill Ackman, the founder of Pershing Square Capital Management, is short Herbalife.
The hedge fund manager considers Herbalife to be a pyramid scheme, according to CNBC.
Shares of Herbalife were last trading down around 8.9%.
UPDATE: Ackman will give his short thesis at a special Ira Sohn Investment Conference tomorrow morning.
Back in June, Ackman told investors in Pershing's Q1 letter that he had new short position.
Ackman is known for being a long-only investor.
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