The European Commission levied the $123M fine because Facebook had said it could not automatically match user accounts on its namesake platform and WhatsApp, but two years later launched a service that did exactly that.
The European Commission on Thursday fined US social media giant Facebook 110 million euros ($122.4 million) for providing incorrect and misleading information on its takeover of WhatsApp.
Facebook had misled the Commission by saying ahead of the 2014 buyout it would be unable to "establish reliable automated matching" between Facebook and WhatsApp user accounts.
But the Commission says that in 2016 WhatsApp offered updates including the possibility of linking user phone numbers with Facebook user IDs.
"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.
Facebook said in a statement the errors made in its 2014 filings were not intentional.
The European Commission, which acts as the EU's competition watchdog, said the fine was "proportionate and deterrent."
The fine would not reverse the Commission's decision to clear the purchase of WhatsApp and was unrelated to separate investigations into data protection issues, the Commission added.
"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," EU Competition Commissioner Margrethe Vestager said in a statement.
"The Commission must be able to take decisions about mergers' effects on competition in full knowledge of accurate facts," she added.