Hindenburg said its research showed that the valuation of IEP units was inflated by more than 75% and that "IEP trades at a 218% premium to its last reported net asset value (NAV), vastly higher than all comparables."

"We've uncovered clear evidence of inflated valuation marks for IEP's less liquid and private assets," it added.

Icahn Enterprises did not immediately respond to a Reuters request for comment. Reuters could not independently verify the claims the short-seller has made in its report.

Shares of Icahn Enterprises fell 5.4% in premarket trading.

Hindenburg invests its own capital and takes short positions against companies. After finding potential wrongdoings, the company usually publishes a report explaining the case and bets against the target company, hoping to make a profit.

Short sellers typically sell borrowed securities and aim to buy these back at a lower price.

(Reporting by Manya Saini in Bengaluru; Editing by Savio D'Souza)