In one of the defining sequences of The Big Short, a film about the 2007-08 financial crisis, a team of hedge fund managers go to Florida. They meet a pair of sleazy mortgage brokers who reveal how the US housing market is propped up by subprime loans to strippers, people with no job or income and immigrants who do not understand the paperwork.

One of the managers calls up his trader and declares: “Hey, there’s a bubble.”