  We introduce a new class of processes for the evaluation of multivariate
equity derivatives. The proposed setting is well suited for the application of
the standard copula function theory to processes, rather than variables, and
easily enables to enforce the martingale pricing requirement. The martingale
condition is imposed in a general multidimensional Markov setting to which we
only add the restriction of no-Granger-causality of the increments
(Granger-independent increments). We call this class of processes GIMP (Granger
Independent Martingale Processes). The approach can also be extended to the
application of time change, under which the martingale restriction continues to
hold. Moreover, we show that the class of GIMP processes is closed under time
changing: if a Granger independent process is used as a multivariate stochastic
clock for the change of time of a GIMP process, the new process is also GIMP.
