Moving off legacy in a regulated business without breaking it

Every CIO in a regulated industry has a system the business depends on, that no one fully understands and that must be replaced. In banking, it is often a core platform that predates the internet. In my own career, that system took two distinct forms: first, a VAX minicomputer running a parking operator’s entire business across nearly 200 New York City locations; later, the on-premises core of a global financial technology company supporting payments, banking and card issuing.