  We briefly sketch the calculation of the effective low-energy $|\Delta
S|=2$-hamiltonian in the next-to-leading order of renormalization group
improved perturbation theory. The result for the coefficient $\eta_3^\star$ is
discussed. Further we present a 1996 update of our phenomenological analysis of
the unitarity triangle where we include the information available on
$B^0-\bar{B^0}$-mixing.
