Bailed out by taxpayers, the big banks are emerging from the financial crisis larger and more concentrated than ever. Their very size offends market competition. Entities that are too big to fail cannot be disciplined by the market. Worse, their size and wealth also undermine democratic accountability. That's why changing the industry's business model and breaking up the banks that are too big to fail are vital steps towards the new economy that we build out of the ruins of the old. This fight must go on.