Cumulative fraction of the formation redshift of haloes, z_form, for haloes inside the FVS (solid red line, top panel), all haloes (solid black line, top panel), and S8+ haloes (dashed red line, top panel). Bottom panel: mean number of galaxies for the halo mass range 10¹⁴ − 5 × 10¹⁴ M_⊙ h⁻¹ as a function of the formation redshift. The line styles are the same as in the top panel.