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 ...
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Chapter 4<br />
Characterization of <strong>de</strong>p<strong>en</strong><strong>de</strong>nce of<br />
multidim<strong>en</strong>sional Lévy processes<br />
4.1 Introduction to <strong>de</strong>p<strong>en</strong><strong>de</strong>nce mo<strong>de</strong>lling<br />
Many financial applications require a multidim<strong>en</strong>sional mo<strong>de</strong>l with jumps, taking into account<br />
the <strong>de</strong>p<strong>en</strong><strong>de</strong>nce b<strong>et</strong>we<strong>en</strong> compon<strong>en</strong>ts. However, such mo<strong>de</strong>ls are more difficult to construct than<br />
one-dim<strong>en</strong>sional ones and the applications continue to be dominated by (geom<strong>et</strong>ric) Brownian<br />
motion.<br />
A simple m<strong>et</strong>hod to introduce jumps into a multidim<strong>en</strong>sional mo<strong>de</strong>l is to take a multivariate<br />
Brownian motion and time change it with a one-dim<strong>en</strong>sional increasing Lévy process.<br />
This approach, advocated in [36, 79], allows to construct multidim<strong>en</strong>sional versions of many<br />
popular one-dim<strong>en</strong>sional mo<strong>de</strong>ls, including variance gamma, normal inverse Gaussian and g<strong>en</strong>eralized<br />
hyperbolic process. The principal advantage of this m<strong>et</strong>hod is its simplicity and analytic<br />
tractability; in particular, processes of this type are easy to simulate. However, the range of<br />
<strong>de</strong>p<strong>en</strong><strong>de</strong>nce patterns that one can obtain using this approach is quite limited (for instance, in<strong>de</strong>p<strong>en</strong><strong>de</strong>nce<br />
is not inclu<strong>de</strong>d), and all compon<strong>en</strong>ts must follow the same param<strong>et</strong>ric mo<strong>de</strong>l (e.g.,<br />
either all of the compon<strong>en</strong>ts are variance gamma or all of the compon<strong>en</strong>ts are normal inverse<br />
Gaussian <strong>et</strong>c.)<br />
To be more specific, suppose that two stock price processes {St 1 } t≥0 and {St 2 } t≥0 are mod-<br />
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