Schromgens emphasized Trivago's strong brand recognition in the U.S. and Europe as key to its success. Instead of having to rely on paid search advertising, three out of four bookings that originate on Trivago come from customers who went directly to the site on their own accord, he said. Kayak CEO Steve Hafner has called Trivago "irritating." The German company advertises aggressively on TV to gain market share, and studies exactly what kind of ads perform best, a method it highlighted to public investors last year. "The global market and the online market are growing strongly," Schromgens said. "I don't look at competitors."