Yes it does. About 10 years ago, John Bahcall at Princeton University did a detailed calculation of how fast stars in the neighborhood of the Sun should be moving if only the gravitational fields of the visible stars were producing the motions of the stars. He found that there was about 50 percent less mass per cubic parsec to account for the stellar velocities. In essence, he weighed the local mass of the Milky Way and found that the visible stars account for only 1/2 the total 'gravitational' mass. he proposed that there is also a population of very low mass, dwarf stars or 'something else' which is contributing nearly as much mass as what we see in the visible stars. As yet we do not know what this 'population' consists of.