Growing concerns about the power of big tech companies probably won’t be enough to derail Google’s planned $2 billion acquisition of Fitbit, antitrust experts say. That’s despite increasing scrutiny from European regulators and a recent complaint about the deal from 20 consumer and online groups.

Google announced last November its intention to grab the struggling maker of eponymous activity-tracking bands and smartwatches. Fitbit once dominated the market for so-called smart wearables, but an onslaught from Apple at the high end and Chinese rivals like Xiaomi at the low end decimated its business. The $2 billion acquisition price was a fraction of Fitbit’s stock market value when it went public in 2015. At the same time, Google’s own wearable platform has failed to gain much traction in the market, and the merger could give a boost to both companies’ efforts.

But regulators in the European Union have many questions about the deal, focusing particularly on whether Google gaining access to the health and fitness data of tens of millions of Fitbit users could somehow strengthen the company’s dominance of digital advertising and search—not to mention sideline other health apps on Google’s Android platform. The EU has sent a 60-page questionnaire to Google and Fitbit rivals seeking their views, the Financial Times reported on Wednesday.

Also on Wednesday, 20 groups including Public Citizen and the Open Markets Institute asked regulators to block the deal, warning that the merger could lead to the misuse of customer data.

Fitbit declined to comment.

Google said there was no reason for the deal to be blocked. “This deal is about devices, not data,” the company said in a statement. “The wearables space is highly crowded, and we believe the combination of Google’s and Fitbit’s hardware efforts will increase competition in the sector, benefiting consumers and making the next generation of devices better and more affordable.”

Google is already under scrutiny by U.S. regulators in a broader antitrust probe of the search and advertising markets.

The problem for those hoping to see the deal blocked is that neither company has a large enough share of the wearables market to cause problems for other competitors, and U.S. law offers little rationale to stop a merger of companies not in the same business, says David Balto, an antitrust attorney and the former policy director of the Federal Trade Commission during the Microsoft antitrust case.

“It would be extraordinarily difficult to bring a case,” Balto says.

Fitbit had less than 5% of the wearables market in 2019, according to data from IDC. Apple led the market with 32% of device shipments, Xiaomi was second with 12%, Samsung was third at 9%, and Huawei ranked fourth with 8%. None of those companies use Google’s wearable-software platform, currently called Wear OS.

The European Union is also unlikely to try to block the merger of two U.S-based companies, although it could look to impose limits on the combined company around the use of customer data.

Some academics have suggested that big tech companies have used small add-on acquisitions to expand their market power inappropriately, but there’s no legal precedent for using the argument to block a merger.

“Fitbit isn’t a Google competitor, exactly. If it were, blocking the merger would be easy,” says Mark Lemley, a law professor at Stanford and the author of a paper on the harm of such mergers. “But neither is it unrelated. Google is building a portfolio of related businesses that collect data on their users, and as that portfolio gets bigger it gets harder to compete with them on a level playing field in any one of those businesses.”

But it’s almost impossible under current law to stop the combination of two companies not in the same line of business, known as vertical mergers, on customer data grounds or any others. Balto points to the recent case in which a court overrode government objections to AT&T’s purchase of Time Warner.

“There are no successful oppositions to vertical mergers like this,” he says. “Fitbit is a Lilliputian compared to the size of assets Time Warner possessed in their relevant markets in that case.”

The point of the letter from the 20 opposition groups was that the merger should be scrutinized and even blocked under current law as a danger to potential or future competition, says Charlotte Slaiman, competition policy director at Public Knowledge and a former FTC attorney herself. “Potential competition is an angle that hasn’t been taken seriously enough, but it is a part of our law,” she says.

Still, U.S. law should be strengthened to take into account the power of digital platforms and the ways big tech companies have used mergers to reduce competitive threats, she adds. “We really need new rules and laws that are focused on digital platforms, because even if we have very effective antitrust enforcement it’s not going to be enough to address the full problem here,” Slaiman says.

(Update: This story was updated on July 2, 2020, with a comment from Google.)