31.05.2014 Views

Processus de Lévy en Finance - Laboratoire de Probabilités et ...

Processus de Lévy en Finance - Laboratoire de Probabilités et ...

Processus de Lévy en Finance - Laboratoire de Probabilités et ...

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Abstract<br />

This thesis <strong>de</strong>als with the mo<strong>de</strong>lling of stock prices by the expon<strong>en</strong>tials of Lévy processes.<br />

In the first part we <strong>de</strong>velop a non-param<strong>et</strong>ric m<strong>et</strong>hod allowing to calibrate expon<strong>en</strong>tial Lévy<br />

mo<strong>de</strong>ls, that is, to reconstruct such mo<strong>de</strong>ls from the prices of mark<strong>et</strong>-quoted options. We<br />

study the stability and converg<strong>en</strong>ce properties of this calibration m<strong>et</strong>hod, <strong>de</strong>scribe its numerical<br />

implem<strong>en</strong>tation and give examples of its use. Our approach is first to reformulate the calibration<br />

problem as that of finding a risk-neutral expon<strong>en</strong>tial Lévy mo<strong>de</strong>l that reproduces the option<br />

prices with the best possible precision and has the smallest relative <strong>en</strong>tropy with respect to a<br />

giv<strong>en</strong> prior process, and th<strong>en</strong> to solve this problem via the regularization m<strong>et</strong>hodology, used in<br />

the theory of ill-posed inverse problems. Applying this calibration m<strong>et</strong>hod to the empirical data<br />

s<strong>et</strong>s of in<strong>de</strong>x options allows us to study some properties of Lévy measures, implied by mark<strong>et</strong><br />

prices.<br />

The second part of this thesis proposes a m<strong>et</strong>hod allowing to characterize the <strong>de</strong>p<strong>en</strong><strong>de</strong>nce<br />

structures among the compon<strong>en</strong>ts of a multidim<strong>en</strong>sional Lévy process and to construct multidim<strong>en</strong>sional<br />

expon<strong>en</strong>tial Lévy mo<strong>de</strong>ls. This is done by introducing the notion of Lévy copula,<br />

which can be se<strong>en</strong> as an analog for Lévy processes of the notion of copula, used in statistics<br />

to mo<strong>de</strong>l <strong>de</strong>p<strong>en</strong><strong>de</strong>nce b<strong>et</strong>we<strong>en</strong> real-valued random variables. We give examples of param<strong>et</strong>ric<br />

families of Lévy copulas and <strong>de</strong>velop a m<strong>et</strong>hod for simulating multidim<strong>en</strong>sional Lévy processes<br />

with <strong>de</strong>p<strong>en</strong><strong>de</strong>nce giv<strong>en</strong> by a Lévy copula.<br />

Key words: Lévy processes, option pricing, calibration, inverse problems, regularization,<br />

ill-posed problems, relative <strong>en</strong>tropy, copulas, <strong>de</strong>p<strong>en</strong><strong>de</strong>nce

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!