Facebook INC's shares fell Wednesday following the uncovering of emails purportedly revealing Chief Executive Officer Mark Zuckerberg's involvement in controversial privacy practices, the Wall Street Journal reported.

The emails were discovered as the social media giant attempts to respond to a federal privacy investigation. Sources within the company fear that the emails could damage the Facebook brand if they became public.

The Federal Trade Commission (FTC) had requested that Facebook turn over emails related to the Cambridge Analytica scandal. The FTC is investigating whether the scandal was a violation of a 2012 consent decree agreement between the commission and Facebook INC.

The company denied that Zuckerberg had committed any wrongdoing.

"We have fully cooperated with the FTC’s investigation to date and provided tens of thousands of documents, emails and files. We are continuing to work with them and hope to bring this matter to an appropriate resolution. Facebook and its executives, including Mark, at all times strive to comply with all applicable law, and at no point did Mark or any other Facebook employee knowingly violate the company´s obligations under the FTC consent order," a Facebook spokesman stated in an email.

Facebook INC shares dropped 2.5% to $173.64 following the report.