Chicago: Heavy machinery manufacturer Caterpillar Inc was under raid by Federal authorities  at its three locations on Thursday prompting a sharp sell-off in the company’s stock.

A spokeswoman for the U.S. Attorney Office for the Central District of Illinois, Sharon Paul, confirmed that federal law enforcement officials conducted searches at locations in Peoria, East Peoria and Morton, Illinois, but did not say why federal agents raided the three locations.

Caterpillar, in a statement issued on Thursday afternoon, said that the search may be related to an Internal Revenue Service investigation on profits earned by a Swiss subsidiary. It said that “while the warrant is broadly drafted, we believe the execution of this search warrant is regarding, among other things, export filings that relate to the CSARL matter first disclosed in Caterpillar’s Form 10-K filed on February 17, 2015, and updated in Caterpillar’s most recent Form 10-K filed with the SEC on February 15, 2017

Agencies involved in the search included the IRS’ Criminal Investigation Division, the U.S. Department of Commerce’s Bureau of Industry and Security’s Office of Export Enforcement, and the Federal Deposit Insurance Corp.’s Office of Inspector General, Paul said.

Officials at the agencies could not be reached for comment.

Caterpillar shares fell 4.3 percent to close at $94.36 on the New York Stock Exchange after trading as low as $92.84.