Finite Unification and Top Quark Mass

In unified gauge theories there exist renormalization group invariant relations among gauge and Yukawa couplings that are compatible with perturbative renormalizability, which could be considered as a Gauge-Yukawa Unification. Such relations are even necessary to ensure all-loop finiteness in Finite Unified Theories, which have vanishing $\beta$-functions beyond the unification point. We elucidate this alternative way of unification, and then present its phenomenological consequences in $SU(5)$-based models.