(U − V)_{rest − frame} versus stellar mass in GOODS-S, GOODS-N and COSMOS (from left to right) in different redshift intervals (increasing from bottom to top). Red circles and blue triangles show Type 2 and Type 1 AGN hosts, respectively, and the y-axis represents host-only colours. Black small dots identify the inactive population. Vertical dashed lines indicate the mass bins used in this analysis.