Christopher Jon Bjerknes
The FTC investigates potential antitrust violations. The Federal Trade Commission has published a brochure in pdf format which you can download here:
Page seven of the brochure provides the following contact information:
If you wish to submit confidential information, send it by mail and mark it "Confidential."
Mail: Federal Trade Commission
Bureau of Competition-H374
Washington, D.C. 20580
Everyone is equally free to confidentially inform the FTC of potential monopolies and other antitrust violations which obstruct free and fair trade.