“We think Icahn, a legend of Wall Street, has made a classic mistake of taking on too much leverage in the face of sustained losses: a combination that rarely ends well,” Hindenburg said in the report.

Icahn Enterprises didn’t immediately respond to a request for comment from Bloomberg News. The firm’s shares were down 15% at 11:32 a.m.

The missive pits Icahn, 87, against Hindenburg’s founder Nathan Anderson, who has made a name for his research firm in recent years by targeting corporate giants like payments company Block Inc. and billionaire Gautam Adani’s business empire.

In Tuesday’s report, Hindenburg claimed Icahn Enterprises’ value is inflated by 75% or more, noting that it trades at a premium of more than 200% to its net asset value. Other closed-end holding companies like Dan Loeb’s Third Point and Bill Ackman’s Pershing Square trade at discounts to their NAV, according to Hindenburg.

The report also raises questions about the size of Icahn Enterprises’ dividend yield and the way in which it has been financed in recent years.

“Icahn has been using money taken in from new investors to pay out dividends to old investors,” Hindenburg said in the report. “Such Ponzi-like economic structures are sustainable only to the extent that new money is willing to risk being the last one ‘holding the bag.’”

While Hindenburg has been active since 2018, when Anderson incorporated the company from an apartment in New York, Icahn has been stalking the corporate world for around 50 years.

A decade ago, he and activist hedge-fund manager Bill Ackman went to war over Herbalife Ltd., with Ackman calling the nutritional-supplements company’s model a pyramid scheme and going public with a $1 billion short bet. Icahn, who at one point owned almost a quarter of Herbalife’s shares, defended the multilevel-marketing model and publicly assailed Ackman for years — on stages and television, in documentaries and online — after an initial CNBC phone-in argument between the two billionaires.

In 2015, a debate at a Delivering Alpha conference between Icahn and BlackRock Inc. Chief Executive Officer Larry Fink quickly devolved into a verbal slugfest. Icahn called an open letter by Fink, which argued that corporate CEOs shouldn’t repurchase shares just to satisfy activists, a “sales pitch for BlackRock” and called the firm “an extremely dangerous company” over its exchange-traded funds.

More recently, Icahn has battled with DNA-sequencing company Illumina Inc., saying the board of the company set a “new low” in governance by pursuing its acquisition of Grail Inc. over antitrust regulators’ objections. In a meeting with Illumina CEO Francis deSouza and Chairman John Thompson in early March, Icahn was quoted as saying he “would not even support Jesus Christ” as an independent candidate over his board nominees who “answer to me.”

Icahn said later that month that Illumina had “taken out of context certain things that were supposedly said” during discussions meant to be private “in the hopes of achieving peace rather than war.”

On average, companies targeted by Hindenburg fell about 15% the day after a negative report appeared and were down 26% six months later, according to February calculations by Bloomberg News.