U.S.-based online travel agency Priceline.com Inc. has exceeded our performance expectations as the company continues to gain market share in key markets. We are revising our rating outlook on Priceline.com to positive from stable. The 'BBB' corporate credit rating is affirmed. The positive outlook reflects our expectation that the company will adhere to its moderate financial policy and performance will remain fairly robust, despite difficult comparisons and macroeconomic weakness in several of its European markets. CHICAGO (Standard&Poor's) Sept. 6, 2013--Standard&Poor's Ratings Services today revised its rating outlook on Norwalk, Conn.-based online travel agency Priceline.com Inc. to positive from stable. We affirmed our existing ratings, including our 'BBB' corporate credit rating. The outlook revision to positive is