In fact, financial markets produce outcomes which are akin to public goods – they involve externalities in that they benefit all without incurring any costs; and they are nonrival in their consumption -– they do not exclude any from their benefits. I would hesitate, however, to classify any market outcome as a public good for fear of being charged with heresy.
In 1980, before geographic deregulation, the high-profit share of assets in the sixteen unitbanking states (those that did not permit any form of branching) was much less than the high-profit share in the twelve states that have permitted branching since the 1930s or earlier. This difference disappears completely by 1994.