The European Commission, the EU’s executive branch, said Monday that it’s classing Booking Holdings as an online gatekeeper and that the company’s Booking.com hotel reservation site meets the threshold to be classed as a “core platform service” under the 27-nation bloc’s Digital Markets Act. The sweeping set of rules is designed to prevent Big Tech platforms from dominating online markets.

European Commission Executive Vice President Margrethe Vestager said the decision means that vacationers “will start benefiting from more choice and hotels will have more business opportunities.”

The company said it has “been working with the European Commission for some time as we anticipated today’s decision. We are reviewing their designation decision now and will continue to work constructively with them as we develop solutions to comply.”

Booking Holdings, based in Norwalk, Connecticut, owns a slew of other travel sites including Cheapflights, Kayak.com and Priceline as well as restaurant reservation platform OpenTable, but those platforms aren’t included in the EU decision.

Since the rules took effect earlier this year, half a dozen companies have already been classified as online gatekeepers. Some including Apple, Google and Meta are already facing investigations into whether they’re doing enough to comply.

Under the DMA, platforms must comply with a list of do’s and don’ts – such as not giving preference to their own services over rivals – under threat of hefty financial penalties or even breaking up businesses. The rules are designed to make digital markets “fairer” and more competitive by breaking up closed tech ecosystems that lock consumers into a single company’s products or services.

The commission said Booking.com “now has six months to comply with the relevant obligations under the DMA, offering more choice and freedom to end users and fair access of business users to the gatekeeper services.”