- Bill Ackman said Tuesday that there's a "karmic quality" to Hindenburg Research's attack on his old rival Carl Icahn.
- The two activist investors feuded over a decade ago when Ackman made a $1 billion bet against Herbalife.
Bill Ackman took aim at his old rival Carl Icahn Tuesday after short seller Hindenburg Research attacked the latter's business empire.
"There is a karmic quality to this short report that reinforces the notion of a circle of life and death," Ackman tweeted. "As such, it is a must read."
Ackman's jibe came after Hindenburg disclosed a short position against Icahn Enterprises (IEP) that led to its shares plunging 20%, and Icahn's own personal fortune falling by around $10 billion.
Hindenburg said that the Wall Street legend's holding company used inflated asset valuations and "ponzi-like economic structures" to move money from new investors to older ones.
Icahn hit back against the short-seller, saying that he stood by IEP's public disclosures.
"We believe the self-serving short seller report published by Hindenburg Research today was intended solely to generate profits on Hindenburg's short position at the expense of IEP's long-term unitholders," he said in a statement.
"We stand by our public disclosures and we believe that IEP's performance will speak for itself over the long term as it always has," Icahn added.
Ackman and Icahn feuded over a decade ago after Ackman made a $1 billion bet against Herbalife, which he alleged was a pyramid scheme. Icahn responded by taking a large stake in the company.
The billionaires' battle over the multi-marketing firm eventually came to a head on live television in 2013.
In a CNBC interview, Icahn called Ackman a "liar" and told the investor: "I wouldn't invest with you if you were the last man on Earth."
"This is not a guy who keeps his word," Ackman responded. "This is a guy who takes advantage of little people."
Read more: The short seller that took on Asia's richest man has a new target: Wall Street legend Carl Icahn