It probably has to do with the fact that nowadays a bank needs 10 million euros of equity to get started in europe. also, the founders/CEO need to prove three y

It probably has to do with the fact that nowadays a bank needs 10 million euros of equity to get started in europe. also, the founders/CEO need to prove three years of academic and three years of practical experience, essentially shrinking down the people that are allowed to start new banks to existing bankers who most likely have no incentive to leave the large bank. This means the regulators are implicitly encouraging the formation of an oligopoly because they have enacted heavy regulation in response to large bank failures. It is kind of ironic.