Reuters/ Eduardo Munoz
Bill Ackman.
The webcast will feature a video called "The American Dream Denied." It will air at 11:30 AM ET
"Herbalife has attempted to convince regulators, elected officials, and the public that it has cleaned up its act and made substantial improvements to its business model. But the stories of Herbalife distributors show that millions of people are still being harmed by the company every day," Pershing Square said in a statement.
"The changes the company has made do not impact Herbalife's pyramidal compensation plan or the predatory practices Herbalife uses to deceive aspiring entrepreneurs."
Shares of Herbalife were last down 4.19%, or down $1.98, at $43.19 per share.
For more than three years, Ackman has been crusading against Herbalife, a multi-level marketer that sells nutritional shakes and weight-loss products.
In late December 2012, Ackman publicly declared via a 342-slide presentation that he was short $1 billion worth of Herbalife. He believes the company is operating as a "pyramid scheme" that targets poor people. It's his contention that regulators, specifically the Federal Trade Commission, will shut the company down.
Herbalife has always denied Ackman's allegations.
In March 2014, the FTC opened an investigation into the company. There hasn't been an update in that area.
It's believed that Ackman shorted Herbalife in the mid-$40s. In October 2013, he repositioned about 40% of his $1 billion equity short position for put options in an effort to reduce risk.
Ackman has said multiple times that he would take his Herbalife short "to the end of the earth."
Ackman is known for being a mostly long-only investor who makes large, concentrated bets in a handful of stocks. Herbalife is his only short. It's also the only bet that's playing out in his favor this year.
Pershing Square Holdings, the fund's publicly traded vehicle, has fallen 11.2% through January 31. Meanwhile, Pershing Square International has fallen 9.3% in the first month of 2016.
We've reached out to Herbalife for comment, and will update if we hear back.