The packs of panels, made available cyclically at the outlet of a dividing machine and arranged side by side, are transferred to a station wherefrom they can be discharged, at the same time, either into a conventional stacking unit of the wedge and lifting platform type, or - after a 90° rotation - into a composite transport runway where said packs will be arranged either similarly side by side or after each other. Arranged laterally of said runway, there are parallel rows of suitable lifting platforms whereon suitable means will stack the packs of panels coming from said transport runway, so that panels of the same size will be stacked on each platform. Finally, means are provided to discharge the stacks of panels from the various lifting platforms and transfer said stacks to conveying and sorting means.