An example system includes an advancement mechanism to drive print medium into a stacking region, a clamping mechanism, and a controller. The clamping mechanism includes a trailing edge clamping arrangement in a trailing edge portion of the stacking region and at least one downstream clamping arrangement in a downstream portion of the stacking region, the downstream portion being downstream of the trailing edge portion. The controller is to sequentially actuate the trailing edge clamping arrangement and the at least one downstream clamping arrangement when the advancement mechanism transports a print medium into the stacking region.