Market Insider

Mallinckrodt shares tank as short-seller Andrew Left claims CEO commits fraud

Mark Trudeau, chief executive officer of Mallinckrodt Plc, speaks during a Bloomberg Television interview in New York, U.S., on Tuesday, Dec. 8, 2015.
Chris Goodney | Bloomberg | Getty Images

Shares of drugmaker Mallinckrodt plunged 12.02 percent Wednesday after long-time short-seller Andrew Left accused the firm's CEO of committing securities fraud.

"Mallinckrodt CEO Mark Trudeau has been caught red handed committing securities fraud — exposed by none other than the newly released Medicare drug-spending dashboard," said Left, the executive editor of the Citron Research newsletter, in a Wednesday note. He also alleged Trudeau committed fraud by lying about the firm's dependence on the Medicare system.

"This long-promised, just released public information database demonstrates that HP Acthar Gel is The Single Most Expensive Drug per Treatment as reimbursed by Medicare / Medicaid," he said.

Mallinckrodt did not immediately respond to CNBC's comment request. The Securities and Exchange Commission declined to comment.

Mallinckrodt 5-day chartSource: FactSet

HP Acthar is a prescription gel used to treat multiple sclerosis.

Left has not been short for words when it comes to Mallinckrodt.

In March, Left said on "Fast Money" that Mallinckrodt makes Valeant look like a "choirboy" in comparison and that Mallinckrodt's drug Acthar is the "poster child" of price gouging.

—CNBC's Christine Wang contributed to this report.