  We analyze constraints on the anomalous $Wtb$ couplings from $B$-physics
experiments, performing a correlated analysis and allowing all anomalous
couplings to differ simultaneously from their Standard-Model (SM) values. The
$B$-physics observables allow one to probe three linear combinations out of the
four anomalous couplings, which parameterize the $Wtb$ vertex under the
assumption that the SM symmetries remain the symmetries of the effective
theory. The constraints in this work are obtained by taking into account the
following $B$-physics observables: the $\bar B^0-B^0$ oscillations, the
leptonic $B\to \mu^+\mu^-$ decays, the inclusive radiative $B\to X_s\gamma$
decays, and the differential branching fractions in the semileptonic inclusive
$B\to X_s \mu^+ \mu^-$ and exclusive $B\to (K,K^*)\mu^+\mu^-$ decays at small
$q^2$, $q$ the momentum of the $\mu^+\mu^-$ pair. We find that the SM values of
the anomalous couplings belong to the 95\% CL allowed region obtained this way
but lie beyond the 68\% allowed region. We also report that the distributions
of the anomalous couplings obtained within our scenario differ from the results
of the 1D scenario, when only one of the couplings is allowed to deviate from
its SM value.
