Shares of
Since December 18, the trading session before Ackman confirmed his short, shares of Herbalife are up more than 3.7%.
On December 24, the stock hit a 52-week low of $24.24 a share and has since rallied back in recent weeks.
Shares of Herbalife closed up $4.06, or 10.14%, to end at $44.08 yesterday. The stock was last up in pre-market trading this morning.
Check out this chart of Herbalife shares from December 18 to Jan. 14:
Pershing Square is shorting more than 20 million shares of Herbalife — a multi-level marketing company that sells nutrition and weight loss products.
Last month, Ackman gave a three-hour long 342-slide presentation at a special Sohn Conference event detailing his short thesis. His short is predicated on his belief that Herbalife is a pyramid scheme.
Ackman has a price target of zero and believes the company is going to fail.
Following Ackman's presentation, Herbalife came out said that he used outdated and inaccurate information for his presentation. The company then held an investor and analyst day in January to rebut Ackman's claims.
The fund manager didn't seem impressed with their rebuttal and said he would release an updated presentation.
Ackman, who has a reputation on the Street as an activist investor who tries to transform businesses, has launched a website for his short called FactsAboutHerbalife.com. He has even purchased Google ads when people search keywords related to Herbalife.
He also told CNN Money's Maureen Farrell recently that he's willing to go "to the end of the earth" to see his short play out. That means he would also lobby congress to change the law if regulators deem Herbalife to be a legal business.
A number of hedge fund managers don't agree with Ackman's short and have taken the long side, most notably Daniel Loeb, the founder of Third Point LLC. Loeb, who owns an 8.2% stake in Herbalife, said in a letter to investors that he thinks Ackman's bet against the company is "preposterous."