A large part of US consumer debt in the past decade – such as mortgages and car, credit card and student loans – has been financed by the sale of securities backed by such loans. A large chunk of banks’ profits also came from this market, as they bundled loans into securities and sold them to investors.

The proposed rules from the US Treasury aimed at making the securitised debt markets safer crystallised what had already been a radical shift in investors’ perceptions of securities backed by loans, and in the banks’ business models.