While we have been agonising at the power of the social media companies to dictate the terms on which we live, in another part of the economic jungle a pair of big beasts is threatening the whole basis of market capitalism. If that sounds melodramatic, consider the financial firepower of Blackrock and Vanguard, purveyors of index funds to the masses.

Including the also-ran State Street, those masses have entrusted an almost unimaginable $19tn to these investment houses, or about a tenth of the market value of the world’s listed securities. The entire UK stock market, for example, is worth less than $2tn. The attractions to the owners of the capital are obvious