Risk Managing Bermudan Swaptions in the Libor BGM Model
22 Pages Posted: 17 May 2003 Last revised: 9 May 2011
Date Written: December 23, 2003
This article presents a novel approach for calculating swap vega per bucket in the Libor BGM model. We show that for some forms of the volatility an approach based on re-calibration may lead to a large uncertainty in estimated swap vega, as the instantaneous volatility structure may be distorted by re-calibration. This does not happen in the case of constant swap rate volatility. We then derive an alternative approach, not based on re-calibration, by comparison with the swap market model. The strength of the method is that it accurately estimates vegas for any volatility function and at a low number of simulation paths. The key to the method is that the perturbation in the Libor volatility is distributed in a clear, stable and well understood fashion, whereas in the re-calibration method the change in volatility is hidden and potentially unstable.
Keywords: central interest rate model, Libor BGM model, swaption vega, risk management, swap market model, Bermudan swaption
JEL Classification: G13
Suggested Citation: Suggested Citation