In 1976, Peter Drucker published The Unseen Revolution: How Pension Fund Socialism Came to America. The book opened with a sentence that would have seemed astonishing at the time, and looks vaguely amusing today: “If socialism is defined as ‘ownership of the means of production by the workers’ . . . then the United States is the first truly ‘Socialist’ country.”

Pension fund socialism is based on a very appealing idea: that social change can happen slowly, iteratively, and without much overt conflict. Rather than fighting against their bosses on the factory floor, or against the capitalist state that exists to defend their bosses in the streets, workers could use their power as owners to pressure businesses into acting more responsibly.

And when you add it all up, this power is quite substantial. According to the Office for National Statistics wealth and assets survey, total private pension fund wealth in the UK is £6.1 trillion — 42 percent of total wealth, and much more than double the UK’s annual output. A substantial portion of this pot is, in one way or another, invested in the stock market. In theory, workers could use their power as shareholders to force companies to raise wages, improve conditions, and reduce their carbon footprint.