A few years ago, senior officials at the Bank for International Settlements started ringing alarm bells about the scale of leverage that was quietly building up in the financial system. Back then, though, it was fantastically hard to get American policymakers – let alone bankers – to listen.

In the go-go days of the credit bubble, Washington policymakers blithely assumed that the Western financial system had plenty of capital to cope with any potential risks. Consequently, as one former BIS official admits: “Worrying about leverage wasn’t fashionable at all – no one wanted to hear.”