The “electricity stock exchange” (actually IPEX, the Italian Power Exchange) is a system for bulk exchange of established quantities of electricity, based on an auction mechanism and on the definition of input and withdrawal programmes for the National transmission grid. The programmes and electricity quantities exchanged are regulated on the basis of a free system of demand and supply, subject to verification of their compliance with grid restrictions by Terna. IPEX is made up of the Energy market and the Despatching Service Market.