Bank market power, both in the loan and deposit market, has important implications for credit provision and for Önancial stability. This article discusses these issues through the lens of a simple theoretical framework. On the asset side, banks choose the quality and quantity of loans. On the liability side, they may be subject to depositor runs whenever they o§er demandable contracts. This structure allows us to review the literature on the role of market power for credit provision and stability and also highlight the interactions between the two sides of banksíbalance sheets. Our approach identiÖes relevant channels that deserve further analysis, especially given the rising importance of bank market power for monetay policy transmission and the the rise of the digital economy.