  The possibility that the masses of supermassive black holes (SBHs) correlate
with the total gravitational mass of their host galaxy, or the mass of the dark
matter halo in which they presumably formed, is investigated using a sample of
16 spiral and 20 elliptical galaxies. The bulge velocity dispersion, typically
defined within an aperture of size less than 0.5 kpc, is found to correlate
tightly with the galaxy's circular velocity, the latter measured at distances
from the galactic center at which the rotation curve is flat, 20 to 80kpc. By
using the well known M-sigma relation for SBHs, and a prescription to relate
the circular velocity to the mass of the dark matter halo in a standard CDM
cosmology, the correlation between velocity dispersion and circular velocity is
equivalent to one between SBH and halo masses. Such a correlation is found to
be nonlinear, with the ratio between the two masses decreasing from 2X10^-4 for
halos of 10^14 solar masses, to 10^-5 for halos of 10^12 solar masses.
Preliminary evidence suggests that halos smaller than ~5X10^11 solar masses are
increasingly less efficient -- perhaps unable -- at forming SBHs.
