A Spanish court on Tuesday said it was investigating the US hedge fund Gotham City for allegedly publishing “misleading” information about Spanish pharmaceutical firm Grifols, causing its shares to plunge.

Gotham City released a research note in January accusing the Barcelona-based company, which makes blood plasma-based medicines, of “manipulating” its reported debt and operational results to “artificially reduce” its debt ratio and therefore its financing costs.

Grifols lost around a quarter of their value on the day the document was published. It has repeatedly denied Gotham City’s claims.

The US firm is a prominent “short-seller” hedge fund that borrows stock in a company and sells it in hopes of buying it back cheaper later to return it to the lender and pocket the difference.

Spain’s top criminal court said in a statement it had opened a probe into the possible violation of market and consumer protection laws by Gotham City for allegedly distributing “biased and misleading” information about Grifols to encourage investors to sell their shares.

Gotham earned over 9.4 million euros ($9.9 million) from the sale of shares in Grifols following the publication of its research note that was based on “totally or partially false economic data”, the judge in charge of the probe said in a court document seen by AFP.

The hedge fund has attacked several large companies in recent years. Its accusations can lead to bankrupcy filing as happened in 2014 to Spanish wifi provider Gowex, which went out of business a few months after a damning report into its accounts from Gotham City.