An anchor (1) that can be secured in a drilled hole (2), with an expansion sleeve (10) for anchoring onto a wall of the drilled hole, and with an anchor bolt (20) that passes through the expansion sleeve and that has an expansion section (38) for widening the expansion sleeve, and it also has a sleeve stop (22) that limits axial movement of the expansion sleeve away from the expansion section (38) is provided. At least one rotary catch (24) is provided which non-rotatably couples the expansion sleeve (10) to the anchor bolt (20), and the expansion sleeve has at least one external thread helix (14) for creating an undercut in the wall of the drilled hole.