We argue that the existing literature, which justifies banking regulation by either market failures or regulation capture, cannot explain why banking is one of the most regulated industries and why banking regulation is a relatively recent institution in market economies. We present a new theory of banking regulation based on government failure. We first explain that banking as a market institution is intrinsically stable and effective, since its unique financial structure, i.e. most funds come from deposits, makes it very difficult for a bank to be refinanced when its investment projects are unsuccessful, thereby hardening their budget constraint and disciplining the bank’s investment decisions. However, the advent of modern governments, who have both the resources and incentive to bail out failing banks, destroys the stabilizing mechanism of banking. We call this government failure. Banking regulation is an institutional resolution to the government failure by restricting banks’ investment decisions before they fail. We provide historical as well as contemporary evidence to support the theory and explore predictions of the theory that are not derived in the existing theories.