Left: K-corrected (rest-frame) soft-band (0.5–2 keV) luminosities as a function of redshift for the Stripe 82X (red diamonds), COSMOS-Legacy (blue asterisks; Civano et al. 2015; Marchesi et al. 2015), and CDFS (black crosses) sources. At every redshift, an increase in survey area preferentially identifies higher-luminosity sources. Right: normalized distribution of k-corrected soft-band luminosities for Stripe 82X compared with COSMOS and CDFS: the wide-area coverage of Stripe 82X which probes a large effective volume of the universe, enables the rare, highest luminosity quasars to be uncovered, complementing the parameter space explored by small- to moderate-area surveys. In both plots, only the sources identified with redshifts are plotted, representing 30% of the Stripe 82X sample (which currently has only spectroscopic redshifts) and 91% and 96% of the CDFS and COSMOS-Legacy sample, respectively, where both spectroscopic and photometric redshifts are available.