Snap reportedly kept a dossier called “Project Voldemort,” which tracked Facebook’s alleged unfair practices over the course of several years, the Wall Street Journal reported on Monday. The dossier, named after the villain in the Harry Potter series, includes instances where Facebook discouraged Instagram influencers from including links to Snap and suspicions that the company prevented Snap content from trending on Instagram, the paper reported.

The information could fuel the FTC’s probe of Facebook, which kicked off in June. That’s when the Department of Justice and Federal Trade Commission began inquiries into whether the company and peers Amazon, Apple, and Google had stifled competition and limited consumer choice with aggressive growth tactics. The FTC said it would oversee the probes into Facebook and Amazon, while the DOJ took charge of looking into Google and Apple.

Fortune asked Facebook and Snap for comment on the report and will update this story if they respond. Facebook’s stock price slid 2% in afternoon trading on Monday. Snap was unchanged.

In addition to Snap, the FTC has connected with “dozens of tech executives and app developers,” including entrepreneurs who sold their companies and startups that failed after losing access to Facebook data, as part of its dig into Facebook’s competitive practices, according to the Wall Street Journal report.

Regulators are considering whether Facebook was unfairly stifling competition or buying up companies to eliminate competitors. 

Over the years, Facebook has made numerous acquisitions and become the dominant player in social media, boasting 2.4 billion users and $56 billion in annual revenue. In some cases, instead of buying a rising new startup, the company debuted features similar to those offered by its fast-growing competitors.

For example, Facebook rolled out augmented reality filters in May 2017, allowing users to take add masks and special effects to their selfies—a feature often credited to Snap.