Cosmological dark matter simulation (Virgo Consortium). The final distribution contains many dark matter halos: a few large ones, more medium sized ones, and many small ones.
Resulting mass function of halos (orange solid line). This has a Schechter form, with rising power law to low-mass halos and exponential cut off for high-mass halos.
A plausible guess for the galaxy mass function is simply one galaxy per halo with the cosmic mass ratio of roughly 1/6 (yellow dashed line).