Many banks’ technology engines are decades old, and they struggle to keep up with rising customer expectations, competitive threats and new regulations. Four approaches can guide banks in their modernization efforts, and each approach successively involves greater scope, cost and risk. The first approach focuses on the distribution layer; the second, more common approach involves aspects of the distribution layer together with aspects of the product and transaction-processing layer; the third transforms the core; and the fourth goes all in to cover every layer of the system architecture at once. Success with any given approach hinges on a bank’s starting point, desired destination, appetite for risk and ability to self-fund. When done right, modernization yields benefits around customer experience, operational efficiency, speed to market and reduced risk. The ultimate measure of success is to rapidly take advantage of changing market circumstances.