Matteo Benetton, Peter Eckley, Nicola Garbarino, Liam Kirwin and Georgia Latsi.
Do financial regulations change bank behaviour? Does this create new risks? Under Basel II, some banks set capital requirements based on their internal risk models; others use an off-the-shelf standardised approach. These two methodologies can produce very different capital requirements for similar assets. See Figure 1, which displays a snapshot of recent risk weights for UK mortgages. In a new working paper we show empirically that this discrepancy causes lenders to adjust their interest rates and to specialise in which borrowers they target.
In the world of bank capital regulation, minimum requirementsgraballtheheadlines. But actual capital resources are what absorb unexpected losses. Banks and building societies typically hold resources substantially in excess of requirements – called the capital surplus. One reason is to avoid breaching the minimum due to unforeseen shocks. Another is to build resources in anticipation of requirements arising from growth or regulatory change. The chart shows how capital surpluses (on total requirements including Pillars 1 and 2, and all types of capital) have varied in recent decades. It is based on historical data from regulatory returns.
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”→