Hedge fund manager William Ackman confirmed Friday that a consulting firm working on his campaign against Los Angeles supplement seller Herbalife Ltd. has been subpoenaed by federal authorities and that the FBI has spoken to some of the firm's employees, the Los Angeles Times reports. Ackman's Pershing Square Capital Management has made a $1 billion bet against Herbalife, claiming the company is an illegal pyramid scheme.

For reprint and licensing requests for this article, CLICK HERE.