Billionaire Carl Icahn's reputation as an investment maverick is due in part to his history as a short seller. Now, he's on the other side of a short and finding it uncomfortable.

Days after short seller Hindenburg Research published a report claiming that Icahn Enterprises inflated the worth of its holdings, Icahn disclosed in a quarterly report to the Securities and Exchange Commission that it will need to write down the value of a major commercial high-rise it owns.

Icahn reported that the unnamed tenant could not meet its rent payments, so it terminated the lease, triggering a new appraisal and a likely write-down for the unnamed building from its most recent valuation of $281M. But Hindenburg claimed that Icahn's overvaluation has been far more widespread across the company's holdings — a claim on which it doubled down when it bought an additional short position, this time against Icahn's bonds, Reuters reports.

Despite registering a $270M net loss in Q1, compared to a $323M net gain the year before, Icahn claimed the net value of its assets to be unchanged from Q4 to Q1, holding steady at $5.6B. Icahn attributed its losses to unsuccessful short positions it took against other companies in its quarterly report.

Since Hindenburg's first report, Icahn Enterprise's stock has lost over 36% of its value, The Wall Street Journal reports. Part of that value destruction could be due to the U.S. Attorney’s Office for the Southern District of New York inquiring about Icahn's asset valuation the day after the first Hindenburg report.

Though Icahn said it is cooperating with the federal investigation, its namesake founder blasted Hindenburg for the effects of its accusations in a statement reported by the WSJ.

“Hindenburg Research, founded by Nathan Anderson, would be more aptly named Blitzkrieg Research given its tactics of wantonly destroying property and harming innocent civilians,” Icahn said.