Fuller argues that this is still an important part of traffic for OTAs as Expedia and Booking Holdings spent some $8 billion on advertising in 2017, with a fifth of that money going to TripAdvisor and trivago . However, Booking Holdings pulled back on this area mid-year last year, a move that has weighed, and should continue to weigh, on revenue for this section of the market. Fuller still expects the metadata platforms to account for about 18% of the OTAs spending this year, but hotel meta revenue growth slowed throughout the year in 2017 and longer term. Get the full story at Barron's