Super Micro Computer’s stock price fell sharply on Thursday after The Wall Street Journal reported that the Justice Department was investigating the server maker.

Shares of the company, which has a market capitalization of nearly $24 billion and has been boosted by investor interest in artificial intelligence, fell $54, or about 12%, in afternoon trading.

Citing people familiar with the matter, the Journal reported that the Justice Department has opened an investigation into Super Micro, although the probe is still in its early stages.

The agency’s investigation followed a critical report about Super Micro in August by Hindenburg Research, an investment firm that specializes in short selling, or betting that a company’s stock price will fall. Hindenburg’s report alleged “flagrant accounting disclosures, evidence of undisclosed related party transactions” and other problems at Super Micro, a Silicon Valley maker of computer servers and storage technology.

According to the Journal, a prosecutor with the U.S. Attorney’s Office in San Francisco is seeking information that may be related to a former employee who accused the company of accounting violations and filed a whistleblower lawsuit against Super Micro in April. The Hindenburg report focused in part on the former employer’s allegations.

On August 28, the day after the Hindenburg report, Super Micro announced that it would file its fiscal 2024 annual report late with the Securities and Exchange Commission.

Super Micro declined to comment.

In a letter filed with the SEC on September 3, Charles Liang, founder and CEO of Super Micro, disputed Hindenburg’s claims.

“You may also have heard of a recent report from a short-seller hedge fund that contains false or inaccurate statements about our company, including misleading presentations of information,” he said. “We will address these statements in due course.”

Hindenburg and the Justice Department did not immediately respond to requests for comment.