The Q2 2015 Criteo report reveals that mobile commerce in the U.S. surpassed 30% of ecommerce transactions, with top-quartile retailers reaching 40%. Mobile-optimized sites significantly enhance conversion rates, while dedicated retail apps account for nearly half of mobile transactions for those prioritizing app experiences. Cross-device shopping behavior is prevalent, with consumers using multiple devices for 40% of purchases, highlighting the need for marketers to adapt to this trend.