We analyze the time series of overnight returns for the bund and btp futures
exchanged at LIFFE (London). The overnight returns of both assets are mapped
onto a one-dimensional symbolic-dynamics random walk: The `bond walk'. During
the considered period (October 1991 - January 1994) the bund-future market
opened earlier than the btp-future one. The crosscorrelations between the two
bond walks, as well as estimates of the conditional probability, show that they
are not independent; however each walk can be modeled by means of a trinomial
probability distribution. Monte Carlo simulations confirm that it is necessary
to take into account the bivariate dependence in order to properly reproduce
the statistical properties of the real-world data. Various investment
strategies have been devised to exploit the `prior' information obtained by the
aforementioned analysis.Comment: 10 pages, 5 figures, LaTeX2e, to be published in Physica