(Bloomberg) — Hedge fund manager Bill Ackman sent shares of Herbalife tumbling on Friday after telling CNBC that top investor Carl Icahn is trying to sell his stake in the nutrition company.

Ackman told the news station that investment bank Jefferies Group approached him about buying a portion of Icahn's Herbalife shares. Ackman and his hedge fund, Pershing Square Capital Management, have been betting against Herbalife since late 2012, saying that the company is an illegal pyramid scheme that should be shut down. Herbalife has denied those accusations.

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