The fraction of galaxies that are X-ray AGN with L _[2−10]  > 10⁴³ erg s^-1, as a function of the stellar mass, in the 0.1 < z < 1.2, 0.1 < z < 0.6, 0.4 < z < 0.9and 0.7 < z < 1.2redshift ranges. At low redshift the slope of the relationship shows good agreement with the fraction of galaxies that are classified as AGN based on emission-line criteria (Best et al. 2005), while it seems to evolve in the same way as the radio-loud fraction of galaxies at low stellar masses.