Selection and properties of the HYPERION sample. Left: SMBH mass as a function of redshift. All the reported points (diamonds and stars) are the subsample of 46 hyperluminous (L_bol > 10⁴⁷ erg s⁻¹) quasars with known SMBH masses reported at the end of 2020. The final selected 18 sources are reported as red stars. The curves represent the exponential growth of seed BHs of different masses (labeled) formed at z = 20, assuming continuous accretion (f_duty = 1) at the Eddington rate (λ_Edd = 1; see Sect. 2). The red curve, corresponding to a growing seed of 1000 M_⊙, was used to select the HYPERION sample. Right: distribution of the HYPERION sample in the M_BH vs. L_bol plane (red stars) along with the distribution of the 83 z > 6 quasars with available M_BH. All M_BH are based on single-epoch MgII virial estimator and L_bol is from bolometric correction from the literature as of 2020. M_BH and L_bol were consistently recomputed for all sources assuming the same ΛCDM cosmology and adopting the mass calibration from Vestergaard & Osmer (2009) and a bolometric correction of 5.15 to the 3000 Å luminosity from Richards et al. (2006). Dashed lines report the location of sources emitting a fixed fraction of L_Edd. The contours report the location of the lower redshift (z = 0.7 − 1.9) SDSS-DR7 quasars from Shen et al. (2011) with MgII-derived masses.