A quarter of travelers used Airbnb in the last year, a Morgan Stanley survey found, up from 22% a year ago and 14% a year before that. With 80% of consumers in the U.S. and E.U. already aware of Airbnb, Morgan Stanley’s Brian Nowak thinks the company has largely tapped out the easy growth. With the novelty gone, Airbnb needs new ways to drive usage. Another obstacle for Airbnb is that travelers are still concerned about privacy and safety issues in regards to the service. This year, survey respondents who hadn’t used Airbnb were more likely to cite safety and privacy concerns than they were a year earlier. “A slowing user adoption curve suggests Airbnb is less of a threat to hotels,” Nowak writes. As a result of the survey findings, Morgan Stanley upped its growth estimates for hotel industry “revenue per available room,” a key industry metric. The firm is most optimistic about Marriott and Hilton and has Overweight ratings on both stocks. Get the full story at Barron's Read also "OTAs getting squeezed by Airbnb, hotel chains" and "Will OTA struggles lead to more disruption for hotels?"