Most financial crises have plenty in common. They tend to start in the banking sector and involve excessive borrowing, together with an asset bubble, usually related to property.

The global crisis of 2008 was no different, with the asset bubble focused on US real estate. But my research suggests this crisis had another underlying cause – that some people in the banking sector were playing or “gaming” the system for their own financial gain.

The game being played had several important features. First was the deliberate complexity of the financial products at its core – in particular the products based on pooling residential mortgage loans (called “mortgage-backed securities”) that were sold by banks to other banks and institutional investors.

These products were issued by the very banks that had offered the mortgages to customers who did not earn enough to pay the mortgage interest, and relied on ever-increasing house prices to stay afloat.

Then there are the behavioural biases that pervade decision-making at all levels of the banking industry. My research found that banking can often attract a certain kind of person: those who are prone to overconfidence, excessive risk-taking and, in some cases, psychopathic behaviour.

Such people tend to like complexity for its own sake. But they often do not fully understand the implications of that complexity for the stability of the financial system as a whole. Often they do not care – they are primarily interested in gaming the system to maximise their bonuses.