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Stability of calibration procedures: fractals in the Black-Scholes model

Yiran Cui 1Sebastian Del Baño Rollin 3Guido Germano 1,2

1. University College London (UCL), Gower Street, London WC1E6BT, United Kingdom
2. London School of Economics and Political Science (LSE), Houghton Street, London WC2A2AE, United Kingdom
3. Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom

Abstract

Usually, in the Black-Scholes pricing theory the volatility is a positive real parameter. Here we explore what happens if it is allowed to be a complex number. The function for pricing a European option with a complex volatility has essential singularities at zero and infinity. The singularity at zero reflects the put- call parity. Solving for the implied volatility that reproduces a given market price yields not only a real root, but also infinitely many complex roots in a neighbourhood of the origin. The Newton-Raphson calculation of the complex implied volatility has a chaotic nature described by fractals.

 

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Related papers

Presentation: Oral at Econophysics Colloquium 2017, Symposium A, by Guido Germano
See On-line Journal of Econophysics Colloquium 2017

Submitted: 2017-03-16 15:59
Revised:   2017-03-16 15:59