A blind fastener has a setting head portion and a shank portion having one end connected with the setting head portion and an opposite end with an internal thread or a threaded bolt receptacle. The shank has a sidewall with an outside diameter smaller than the diameter of the setting head portion, and is configured for close reception in an aperture of the workpiece prior to being upset. The sidewall has a deformation area that is disposed between the setting head portion and the internal thread or the threaded bolt receptacle, and is upset radially outwardly to secure the fastener to the workpiece. The deformation area includes a central circumferential region which provides sole weakening for the sidewall.