Abstract

In this paper, we consider the problem of equal risk pricing and hedging in which the fair price of an option is the price that exposes both sides of the contract to the same level of risk. Focusing for the first time on the context where risk is measured according to convex risk measures, we establish that the problem reduces to solving independently the writer and the buyer's hedging problems with zero initial capital. By further imposing that the risk measures decompose in a way that satisfies a Markovian property, we provide dynamic programming equations that can be used to solve the hedging problems for both European and American options. All of our results are general enough to accommodate situations where the risk is measured according to a worst-case risk measure, as is typically done in robust optimization. Our numerical study illustrates the advantages of equal risk pricing over schemes that only account for a single party, pricing based on quadratic hedging (i.e. ϵ-arbitrage pricing), or pricing based on a fixed equivalent martingale measure (i.e. Black–Scholes pricing). In particular, the numerical results confirm that when employing an equal risk price both the writer and the buyer end up being exposed to risks that are more similar and on average smaller than what they would experience with the other approaches.

Highlights

  • One of the main challenges in pricing and hedging financial derivatives is that the market is often incomplete and there exists unhedgeable risk that needs to be further accounted for in pricing

  • In the case of discrete time hedging, we show how the boundaries of such a fair price interval can be obtained by using dynamic programming for both European and American options as long as the convex risk measures employed by the two parties are one-step decomposable and satisfy a Markovian property

  • In the context where the underlying asset follows a geometric Brownian motion, we show for the first time how robust optimization can motivate the use of worst-case risk measures that only consider a subset of the outcome space

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Summary

Introduction

One of the main challenges in pricing and hedging financial derivatives is that the market is often incomplete and there exists unhedgeable risk that needs to be further accounted for in pricing. In the case of discrete time hedging, we show how the boundaries of such a fair price interval can be obtained by using dynamic programming for both European and American options as long as the convex risk measures employed by the two parties are one-step decomposable and satisfy a Markovian property (see Section 2.1 for proper definitions). Our numerical experiments indicate that the fair price interval might converge, as the number of rebalancing periods increases, to the Black- Scholes price when an uncertainty set inspired by the work of [4] is properly calibrated in a market driven by a geometric Brownian motion If supported theoretically, such a property would close the gap between risk neutral pricing and risk averse discrete-time hedging using worst-case risk measures. We further refer the reader to an extensive set of Appendices describing detailed arguments supporting all propositions and lemmas presented in this article

The Equal Risk Pricing Model
Equal Risk Pricing with Convex Risk Measures
Discrete Dynamic Formulations for Equal Risk Pricing Framework
European Style Options
American Style Option
Bellman Equations for Equal Risk Price with Commitment
Bellman Equations for Equal Risk Price without Commitment
On the Value of Hedging Beyond the Exercise Time
Recursive Conditional Value-at-Risk Example
Numerical Study with Worst-case Risk Measures
Comparison with -arbitrage Pricing
Comparison with the Black-Scholes
The Case of American Options
Conclusion
A Analytical Solutions of One-period Example
Analytical Solution for the One Period Equal Risk Model
Analytical Solution for the One Period -arbitrage Model
B Proofs for Section 2
C Proofs for Section 3
D Appendix for Section 4
Bounded Conditional Market Risk Property for U1
Bounded Conditional Market Risk Property for U2
Worst-case Risk Measures with U1 or U2 Satisfying the Markov Property
Findings
Implementation Details Regarding How the Dynamic Program Was Solved
Full Text
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