0749 ET - Marriott International is relying on more hotel conversions to drive room growth. The hotel company added 17,900 net rooms in 2Q, with conversions remaining "an important driver of growth," Marriott says. Conversions represented more than a third of signings and 40% of openings in the first half of the year. Hotel companies have been turning to conversions to keep their room growth numbers high and satisfy investors, as construction costs create more challenges for building new hotels. Marriott's worldwide development pipeline for new rooms reached a new record in the quarter, totaling 629,000 rooms. Marriott is off 4.4% premarket.