The EU’s executive commission expressed concerns the deal would further entrench the US Big Tech’s position in the online ad market.
The EU has stated that Google’s Fitbit plans might include “increasing the already vast amount of data” the company uses to personalize ads.
"Our investigation aims to ensure that control by Google over data collected through wearable devices as a result of the transaction does not distort competition,” said European Commission Executive Vice-President Margrethe Vestager, who also is the EU's competition commissioner.
Google agreed to buy Fitbit in November for $2.1 billion. Privacy, social justice and consumer groups have called on authorities to block the deal, citing privacy and antitrust concerns.
The EU said the deal could expand Google’s “data advantage" and therefore raise barriers for rivals to match Google’s online advertising services.
“This deal is about devices, not data,” said Rick Osterloh, Google's senior vice president for devices and services.
“We’ve been clear from the beginning that we will not use Fitbit health and wellness data for Google ads,” he wrote in a blog post.
The investigation adds more scrutiny of the transaction, which Australia's competition watchdog is also examining.
And it underscores the lead role EU authorities have taken in global efforts to regulate the big technology companies.