By early 2015, mobile payments represented a major new opportunity, but no dominant system had yet emerged. There were over 6 billion mobile subscriptions globally that could enable mobile payments, but a lack of compatibility between different payment systems posed obstacles. While mobile payments grew rapidly in the US, reaching $52 billion in transactions in 2014, the battle among competing standards was still unfolding. For a new technology to achieve dominance, it benefits from network effects that make it more valuable as more people adopt it, through learning effects and network externalities. However, whether winner-take-all markets are good for consumers depends on balancing the network benefits with competitive pressures.