Randomization of Short-Rate Models, Analytic Pricing and Flexibility in Controlling Implied Volatilities

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1. Verfasser: Grzelak, Lech A.
Format: Preprint
Veröffentlicht: 2022
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author Grzelak, Lech A.
author_facet Grzelak, Lech A.
contents We focus on extending existing short-rate models, enabling control of the generated implied volatility while preserving analyticity. We achieve this goal by applying the Randomized Affine Diffusion (RAnD) method to the class of short-rate processes under the Heath-Jarrow-Morton framework. Under arbitrage-free conditions, the model parameters can be exogenously stochastic, thus facilitating additional degrees of freedom that enhance the calibration procedure. We show that with the randomized short-rate models, the shapes of implied volatility can be controlled and significantly improve the quality of the model calibration, even for standard 1D variants. In particular, we illustrate that randomization applied to the Hull-White model leads to dynamics of the local volatility type, with the prices for standard volatility-sensitive derivatives explicitly available. The randomized Hull-White (rHW) model offers an almost perfect calibration fit to the swaption implied volatilities.
format Preprint
id arxiv_https___arxiv_org_abs_2211_05014
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Randomization of Short-Rate Models, Analytic Pricing and Flexibility in Controlling Implied Volatilities
Grzelak, Lech A.
Computational Finance
Mathematical Finance
Portfolio Management
Pricing of Securities
Risk Management
We focus on extending existing short-rate models, enabling control of the generated implied volatility while preserving analyticity. We achieve this goal by applying the Randomized Affine Diffusion (RAnD) method to the class of short-rate processes under the Heath-Jarrow-Morton framework. Under arbitrage-free conditions, the model parameters can be exogenously stochastic, thus facilitating additional degrees of freedom that enhance the calibration procedure. We show that with the randomized short-rate models, the shapes of implied volatility can be controlled and significantly improve the quality of the model calibration, even for standard 1D variants. In particular, we illustrate that randomization applied to the Hull-White model leads to dynamics of the local volatility type, with the prices for standard volatility-sensitive derivatives explicitly available. The randomized Hull-White (rHW) model offers an almost perfect calibration fit to the swaption implied volatilities.
title Randomization of Short-Rate Models, Analytic Pricing and Flexibility in Controlling Implied Volatilities
topic Computational Finance
Mathematical Finance
Portfolio Management
Pricing of Securities
Risk Management
url https://arxiv.org/abs/2211.05014