Economies of Scale is the largest aggregator of accommodations in the world. At the end of 2020, it offered reservations for nearly 2.4 million properties. This included over 430,000 hotels and 1.9 million vacation rentals, apartments, and alternative accommodations 1. In contrast, Marriott ended 2020 with roughly 5,600 hotels and 943,000 rooms 2. For every room that Marriott has, Booking has two-and-a-half properties. Advantage,