Watchdog organizations like the Center for Digital Democracy, Public Citizen and Consumer Action have been urging regulators to block the merger. "If this acquisition is approved," they wrote in a letter (PDF) to the FTC, "Google will further consolidate its monopoly power over Internet-based services." They warned that Google already knows more about consumers than any other company through its extensive portfolio of internet services and should not be allowed to add one more to the list.

They added: "Google already holds a dominant position in the digital marketplace, health data is critical to the future of that marketplace, and the data protection concerns stemming from the acquisition will have far-reaching consequences including a dramatic erosion of consumer privacy."

We've reached out to Google for a statement. When the deal was announced, though, the tech giant said Fitbit users' health and wellness data will not be used for advertisements.