Facebook purchased WhatsApp back in 2014. European Union competition regulators have issued a fine of €110 million to Mark Zuckerberg's firm for providing misleading information about the purchase.
The European Commission described their decision as a "proportionate and deterrent fine".
"The Commission has found that, contrary to Facebook's statements in the 2014 merger review process, the technical possibility of automatically matching Facebook and WhatsApp users' identities already existed in 2014, and that Facebook staff were aware of such a possibility," the Commission said.
This decision does not reverse the Commission's decision to clear the purchase of messaging service WhatsApp and it is separate to ongoing investigations into data protection issues around this.
“Today’s decision sends a clear signal to companies that they must comply with all aspects of EU merger rules, including the obligation to provide correct information,” said Margrethe Vestager, the European commissioner for competition.
Facebook responded to say that any errors discovered by the Commission were unintended.
“We’ve acted in good faith since our very first interactions with the Commission and we’ve sought to provide accurate information at every turn,” a spokesman said. “The errors we made in our 2014 filings were not intentional.”