Facebook hasn't been quiet about copying features made popular by Snapchat and adding them to Instagram and its other apps. Apparently Snap, the parent company of the Snapchat app, kept track of Facebook's competitive moves in a dossier called "Project Voldemort."

Project Voldemort -- a nod to the dark wizard and main antagonist in the Harry Potter book series -- contains files that chronicle Facebook "hardball tactics," according to a report Monday from The Wall Street Journal. Some of these tactics included discouraging influencers from mentioning Snap on their Instagram accounts and preventing Snap content from trending on Instagram, according to the Journal, citing "people familiar with the project." 

Project Voldemort reportedly came to light as part of an antitrust investigation by the Federal Trade Commission into Facebook's business practices. The FTC is talking with a number of current and former Facebook competitors as part of its investigation, according to the Journal. 

Facebook in July confirmed the FTC had opened an antitrust investigation into the company. The investigation was revealed the same day that the FTC announced that it was hitting Facebook with a record $5 billion fine for its earlier privacy mishaps. 

Facebook doesn't just face an antitrust investigation from the FTC. In June, the House antitrust subcommittee announced it was launching an investigation of Facebook, Google and other tech companies. Attorneys general from several states and Washington DC have also joined together to investigate the social network over potential antitrust violations.

Facebook and Snap didn't respond to requests for comment. 

Originally published Sept. 23, 9:15 a.m. PT.
Update, 5:11 p.m. PT: Adds background on other antitrust investigations into Facebook.