The 2016 Nobel Prize in economics has been awarded to Professors Oliver Hart and Bengt Holmström for their contributions to contract theory. The theory offers a wide range of real-life applications, from corporate governance to constitutional laws. And, as the post will hopefully convince you, contract theory is also helpful in regulating banks! To this end, we will unpack the outline of the theory and apply it to a number of real-world conundrums: How to pay banks’ chief executives and traders? How to fund a bank’s balance sheet? How to regulate banks? Continue reading “The art of the deal: what can Nobel-winning contract theory teach us about regulating banks?”→
Two of the country’s largest banks collapse. The subsequent panic brings the banking system to its knees and only a costly government bail-out prevents even greater catastrophe. A radical re-think of regulation is needed. No, it’s not London or New York in 2008. It is Berlin in the 1930s. It’s when risk-weighted capital regulation was born, notably to be used alongside a range of other tools; for example, liquidity requirements and such modern ideas as bonus deferrals and capital conservation. But the idea that no single regulatory measure is likely to be sufficient on its own was forgotten. In 2008 it had to be painfully re-learned making this episode a striking example of the importance of studying past financial crises.
Most large banks assess the capital they need for regulatory purposes using ‘internal models’. The idea is that banks are in a better position to judge the risks on their own balance sheets. But there are two fundamental problems that can arise when it comes to modelling. The first is complexity. We live in a complex world, but does that mean a complex model is always the best way of dealing with it? Probably not. The second problem is a lack of ‘events’ (eg defaults). If we cannot observe an event, it is difficult to model it credibly, so internal models may not work well.
When banks are subject to both a leverage and a risk-weighted constraint they may violate a fundamental law of economics: that of demand. In our theoretical model, some banks constrained by the leverage ratio react to an increase in capital requirements by investing more in the asset. This so-called ‘Giffen’ behaviour is very counterintuitive. One would assume the opposite to be the case: higher capital requirements should discourage lending. In our theoretical model, Giffen behaviour is likely to occur for firms that hold predominantly low-risk weighted asset and are therefore bound by the leverage ratio. The real-world equivalent in the context of mortgages would be building societies and, in the future, ring-fenced banks. Continue reading “Are mortgages like potatoes? Unintended consequences in a world of many constraints”→