Number of close companions per unit comoving volume (﹩n_{c}﹩) plotted vs. ﹩M_{r}﹩ for SDSS and for Millennium. In both cases, ﹩n_{c}﹩ is computed by multiplying the real‐space ﹩N_{c}﹩ by the number density of galaxies. Excellent agreement is seen between the two samples. We conclude that most mergers occur between galaxies with ﹩M_{r}> -21﹩. The right‐hand axis displays the corresponding volume merger rate.