Priceline actually got renamed to Booking Holding earlier this year, to reflect the fact that Booking.com is by far the largest part of their turnover.
Expedia have hotels.com, the main competitor to booking. The plane business and the hotel business are of similar size from what I've seen. Both huge and shadowing everything else.
I just got back from a three week vacation, and the travel-specific site I used most was TripAdvisor. I also used a lot of sites not specific to travel (like google maps and reddit).
Does TripAdivsor not qualify as a "major website about travel"? I don't actually know what share of travel-related web traffic they get, and I realize that Expedia and Priceline both own lots of other sites in the space.
What percentage of TripAdvisor does Expedia still own? The stock looks to be mostly held by various mutual funds although I didn't look very closely and may be missing something.
That's just accounting. Doesn't matter. Businesses are not run independently, they share some employees and services.
When you join the company, they will explain you the portfolio of brands and how they link together. A user might leave a site and spend money somewhere else, but it's alright as long as it stays in the family.
They're independently owned. You could argue that it was just accounting if the two businesses had the same or similar ownership while being two separate entities, but they're two different publicly traded companies with substantially different ownership. They also don't share a single board member. Can you provide some sort of substantive indication that they're operating together (today, as compared to prior to the TripAdvisor spinoff)?
Actually, most travel sites you use are probably owned by Expedia, then priceline.
Together, they own every single major web sites about travel.