A three-sided, progressively-formed threaded fastener is comprised of a plurality of planar longitudinal faces intersecting at comer areas. Shank tabs extend downward from the bottom of each of the faces at the base of the fastener. Threaded regions along the inside surface of the planar faces are coined indentations applied during the formation of the fastener. A plurality of wedge-shaped protrusions extend downward from the comer areas at the base of the fastener. The combination of shank tabs and wedge-shaped protrusions form a clinch profile along the bottom of the fastener so that it may can be affixed to a sheet of metal by clinch fit.