According to Skift Senior Research Analyst Seth Borko, Expedia and Booking generated about $19 of travel sales for every $1 they spent on digital marketing in 2008. However, that efficiency has declined in the interim about 15 percent to $16 in bookings for every marketing dollar spent.

The declining efficiency of performance ad spending coupled with increased competition for consumer attention from hotel and airline direct booking campaigns have caused the online travel agencies to reconsider their approach to brand advertising.