A "problem of twelve" arises when a small number of institutions acquire the means to exert outsized influence over the politics and economy of a nation. The Big Four index funds of Vanguard, State Street, Fidelity, and BlackRock control more than twenty percent of the votes of S&P 500 companies-a concentration of power that's unprecedented in America. Then there's the even-faster rise of private equity funds, such as the Big Four of Apollo, Blackstone, Carlyle, and KKR, which have amassed $2.7 trillion of assets, and are eroding the legitimacy and accountability of American capitalism, not by controlling public companies, but by taking them over entirely, and removing them from public disclosure and scrutiny. This quiet accumulation in the last few decades represents a dramatic transformation in how the American economy operates-a sea change that few of us have noticed and all of us need to consider. Harvard law professor John Coates forcefully calls our attention to what is sure to be one of the major political and economic issues of our time.