The acquisition of companies for their data is concerning in general for regulators, Europe’s antitrust chief Margrethe Vestager said on Thursday, a week after Google bought fitness trackers company, Fitbit.

Alphabet Inc-owned Google paid $2.1 billion for Fitbit to help it take on Apple and Samsung Electronics in the crowded market for fitness trackers and smart watches. Vestager declined to comment on the deal specifically but said there was general unease among regulators when data-heavy companies are the targets of bids.

Google’s deal has triggered calls from competitors to competition enforcers to take a tough line. Fitbit, which helped pioneer the wearable devices craze, has an invaluable trove of health data.

“In general, we have a concern if companies merge because of data,” Vestager told a news briefing at Web Summit.She added that regulators then considered the questions of, does this create a barrier to entry, will this make it more difficult to innovate and does a risk to privacy issues arise from that kind of data coming together.

Vestager has in the last two years handed down more than 8 billion euros in fines to Google for stifling competitors in three separate cases involving its price comparison shopping product, its Android smartphone operating system and in search advertising brokering.