As mobile phones and tablets are in widespread use, the emergence of mobile channel is changing the way customers interact with financial institutions. In this research, we empirically examine how the use of mobile devices can improve customer informedness and affect customer behavior in financial transactions. We use a large-scale customer transaction data obtained from one of the largest commercial banks in the United States. Specifically, we investigate: (1) whether the use of mobile phones and tablets is associated with a higher level of customer informedness and demand for services; and (2) compared to customers that only transact through a PC, whether mobile phone and tablet users are less likely to incur overdraft and credit card penalty fees. This paper contributes new knowledge in omni-channel banking services by examining post-adoption customer behavioral changes using transaction-level observations. We also discuss insights for banks’ managers related to the design of new mobile channel, and strategic management of existing digital and physical channels.