Ackman said he will share the evidence at a presentation in New York on Tuesday.
“You’re going to learn why Herbalife is going to collapse,” Ackman said in an interview on
Ackman has waged a high-profile campaign against Herbalife since December 2012, arguing that the company operates an illegal pyramid scheme. His allegations have prompted investigations by the
Herbalife has denied Ackman's claims, saying it operates a multi-level marketing model that is legal and employed by several other U.S. companies. A company spokeswoman did not immediately respond to a request for comment about Ackman's latest allegations.
Ackman said he shorted Herbalife's stock for more than $1 billion in 2012, betting that the price of its shares would fall. He said the problem is in the way Herbalife pays its independent network of salespeople. The distributors are rewarded more for recruiting new salespeople than for actually selling the company's nutrition and weight-loss products, he said.
On Tuesday, Ackman said, he will present evidence of fraud at "nutrition clubs" that Herbalife salespeople operate at storefronts throughout the United States -- and in other countries.
"The fraud is in the way they fundamentally operate the so-called nutrition clubs, where they talk about places for people to get together and talk about good nutrition and lose weight," Ackman said. "That's not what's happening at these venues."
Ackman said he would make his case in part through internal documents provided by Herbalife employees.
"This will be the most important presentation that I've made in my career," Ackman said. "We won't disappoint."
Herbalife shares lost $6.82, or 11.2%, to $54.02.