A convergent-divergent nozzle for a turbofan engine of a supersonic aircraft, wherein the nozzle has an inner wall and forms a flow channel with a nozzle throat surface and a nozzle exit surface. A trim ring that is displaceable in the axial direction between a first position and a second position is provided, wherein the inner wall of the nozzle and the trim ring are embodied and positioned with respect to each other in such a manner that the trim ring extends at a radial distance to the inner wall in the first position, wherein a ring-shaped bypass channel is provided, extending between the trim ring and the inner wall of the nozzle, and the trim ring abuts the inner wall in the second position.