Evolution of median baryonic (solid lines) and stellar mass (dashed lines) in the inner clump (i.e. enclosed within 1 physical kpc) for stacks of galaxies in 0.5 dex M_* bins. Lines are colour-coded by total stellar mass at redshift z = 0. The median M_* of each bin is shown by the solid circles plotted at t ≈ 13.5 Gyr. The inner clump mass grows gradually in lower-mass galaxies (redder colours), indicating significant gas infall into their central regions and ongoing star formation. The inner clumps of more massive galaxies form early and have little gas left at z = 0.