  Using linear response theory with the dynamical mean-field approximation we
investigate the particle-hole instabilities of the two-band Hubbard model in
the vicinity of the spin-state transition. Besides the previously reported
high-spin--low-spin order we find an instability towards triplet excitonic
condensate. We discuss the strong and weak coupling limits of the model, in
particular, a connection to the spinful hard-core bosons with a
nearest-neighbor interaction. Possible realization in LaCoO3 at intermediate
temperatures is briefly discussed.
