An improved nut-and-bolt assembly reduces tensile stress concentration on the bolt. The assembly has a specially designed nut with a tapered region extending from the nut crown and threaded with the first several bolt threads. The cross sectional area of the tapered region decreases linearly as a function of distance from the crown whereby the tapered region has a convex profile. Each of the bolt threads engaging the tapered region take up an approximately equal amount of longitudinal stress on the bolt.