The U.K. on Wednesday rejected Microsoft Corp.’s bid to buy video game maker Activision Blizzard, citing the potential detrimental effect it could have on consumers due to a lack of competition.

It would have been the biggest tech deal in history if antitrust regulators in Britain had not scuttled the deal on their side of the pond.

“The only effective remedy” to ensuring healthy competition “is to prohibit the merger,” the U.K.’s Competition and Markets Authority said in its final report. All companies involved in the deal said they would appeal.

Regulators in the U.S. and Europe are also scrutinizing the $69-billion, all-cash deal with similar concerns. In the U.S., the Federal Trade Commission has challenged the deal in court, with an in-house trial set to begin Aug. 2. The E.U.’s Competition and Markets Authority is due to hand down a decision on May 22.

The merger would have added to the 60-70% cloud gaming market share that Microsoft already owns globally, the authority said in a statement announcing the decision.

Activision Blizzard makes Call of Duty, World of Warcraft, Diablo, Overwatch and numerous other titles as one of the biggest video game developers in the world. Microsoft sells the Xbox gaming console and operates a cloud-based video game streaming service, as well as the Xbox Game Pass subscription service.

“The merger could make Microsoft even stronger in cloud gaming, stifling competition in this growing market,” the authority said.

Cloud gaming streams to various digital devices, from phones to tablets, and eliminates the need for players to plunk down money for pricey gaming consoles and computers. It allows gamers to play Candy Crush and other mobile games on platforms of their choosing.

Microsoft had made some concessions, agreeing to license Activision titles such as Call of Duty for 10 years in deals it struck with Nintendo and other cloud gaming providers. It offered Sony a similar arrangement but the electronics and gaming giant opposed the acquisition instead.

While the U.K. authority examined those remedies “in considerable depth,” it found that they would create a need for too much oversight and impede cloud computing’s ability to develop organically.

Activision said the move indicated that “the U.K. is clearly closed for business” and vowed to “work aggressively” with Microsoft to get the decision reversed. Microsoft was equally adamant.

“We remain fully committed to this acquisition and will appeal,” Microsoft President Brad Smith said in a statement, adding that the decision would discourage tech innovation and investment in Britain. “We’re especially disappointed that after lengthy deliberations, this decision appears to reflect a flawed understanding of this market and the way the relevant cloud technology actually works.”

With News Wire Services