Since news of the raid broke Thursday morning, the company's stock has dropped more than 4 percent, according to Bloomberg.
DoJ spokesperson Sharon Paul confirmed the investigation to Forbes by telephone, stating that Caterpillar's Peoria, Ill. headquarters and its offices in East Peoria and Morton, Ill. were subject to the law enforcement operation.
A Caterpillar spokeswoman said law enforcement is present in various Peoria-area Caterpillar facilities executing a search warrant.
The company has said that it was cooperating with the investigation, which is being overseen by the US attorney's office for the Central District of IL.
While authorities did not immediately disclose details of the raid, NBC affiliate WEEK reported receiving photos of law enforcement wearing IRS jackets entering Caterpillar's headquarters.
Caterpillar was among several companies, including Apple, that the subcommittee has investigated in recent years. Undistributed profits of the foreign subsidiaries and the movement of cash among some of those units and Caterpillar U.S. subsidiaries were among other issues covered by the subpoena. It's not clear if that investigation is ongoing or completed. The number of vehicles and reports from inside Caterpillar indicate this is a multi-agency effort, including the IRS, FDIC, and The Department of Commerce-Bureau of Industry and Security.
Associated Press writer Matthew Ott contributed from Washington, D.C.