The European Commission on Monday ruled that online Dutch travel giant Booking.com was a big enough gateway between customers and companies to fall under tougher competition rules.

Brussels said it would also launch an investigation into whether X, the platform formerly known as Twitter, would also need to fall in line with the landmark Digital Markets Act (DMA).

What was the decision about?

The DMA is among the most stringent set of regulations targeting huge tech firms' market dominance and leveling the playing field for smaller enterprises.

It places companies under strict obligation to moderate content and seeks to ensure that consumers have greater choice and make it easier for them to switch between services.

The rules also seek to curb monopolies by compelling the companies to tell Brussels about any businesses that they buy, regardless of size.

Booking.com has a market share in Europe of more than 60%, making a clear dominant player.

"Today's good news is: holidaymakers will start benefiting from more choice and hotels will have more business opportunities," said EU competition commissioner Margrethe Vestager.

The EU had already labeled six market gatekeepers: Google parent firm Alphabet, Amazon, Apple, Microsoft, and the TikTok owner ByteDance.

Booking.com now has six months to prepare for compliance with the DMA

Why couldn't the Commission decide about X?

When it came to X, the Commission said the jury was still out after the platform entered a rebuttal.

According to the commission's press release, X has argued that "despite meeting the thresholds, X does not qualify as a[n] important gateway between businesses and consumers." The investigation will take five months, the Commission said.

The commission has alread decided not to assign gatekeeper status to X's advertising service, X Ads.

It said that "although X Ads meets the quantitative designation thresholds under the DMA, this core platform service does not qualify as an important gateway."

rc/lo (AFP, Reuters, dpa)