The private equity industry is used to political abuse. A decade ago a leading German politician likened buyout firms to “locusts” swarming over European industry. In the run-up to the US presidential election in 2016, many of the candidates, including Donald Trump, threatened to clip the locusts’ wings.

Now it is Democratic presidential hopeful Elizabeth Warren who is targeting the firms she says are “vampires” sucking the blood from corporate America. The former Harvard law professor has published proposed legislation to curb the industry with a title that doesn’t mince words: the Stop Wall Street Looting Act.