For twenty years the PUN (Prezzo Unico Nazionale, National Single Price) was the purchase price of electricity on the Italian power exchange. Since 1 January 2025 it has been replaced by the PUN Index GME, the index that the market operator GME (Gestore dei Mercati Energetici) calculates from the results of the Day-Ahead Market (MGP). When a supply contract mentions "PUN", today it refers to this index.
How it is calculated
On the MGP, accepted offers are valued at the marginal clearing price of the zone they belong to. Italy has seven geographical zones: North, Centre-North, Centre-South, South, Calabria, Sicily and Sardinia, in the configuration in force since 1 January 2021. Zonal prices coincide as long as the grid can carry energy from one zone to another; they split when transit limits are saturated.
The PUN Index GME is the average of zonal prices, weighted by the quantities purchased in each zone. Since delivery day 1 October 2025, 15-, 30- and 60-minute products are traded on the MGP and GME calculates the index for every quarter-hour, the minimum market time unit; prices continue to be published on an hourly basis as well.
What changed on 1 January 2025
Legislative Decree 210/2021 (Article 13) and the decree of the Minister of Environment and Energy Security of 18 April 2024 provided that, from 1 January 2025, wholesale purchases too are valued at zonal prices. To avoid passing differences between zones on to customers, the regulator ARERA, with Resolution 304/2024/R/eel, introduced a compensation component equal to the difference between the zonal price and the PUN Index GME, applied to purchases on the MGP. As a result, buyers continue to pay a single national value.
The mechanism is explicitly transitional: the decree provided for its application at least until 31 December 2025 and states that any change takes effect no earlier than twelve months after its adoption. As of October 2026, GME documentation describes the compensation component as still applied. For indexed contracts already in force, ARERA clarified that the switch from PUN to PUN Index GME is not a unilateral change: sellers were asked to inform customers in the first relevant bill.
For a business: what to look at
- In the contract. The typical formula is "PUN Index GME + spread". Check which value of the index applies (monthly average, average by time band, hourly or quarter-hourly value matched to metered withdrawals), whether the spread is fixed in €/MWh for the whole term, and whether the price applies to the energy withdrawn or to that energy increased by grid losses.
- In the invoice. The index value used for the month can be verified: GME publishes MGP results and monthly average prices by time band. Dispatching, transport, system charges and taxes, which the PUN does not include, are added to the energy price.
- The decisions it affects. Staying indexed, fixing the price or combining the two in tranches is a risk management choice, to be linked to the budget and to the company's ability to absorb fluctuations. It should be made before starting procurement, not after receiving the offers.
- Typical mistakes. Comparing offers by looking only at the spread; mistaking the PUN for the all-in price; ignoring the consumption profile, because with hourly indexation those who consume mainly in the most expensive hours pay on average more than the monthly value; assuming that the zonal price applies to one's own plant, whereas for buyers the reference remains national.
To review the price formula of your contract together with an IPGS ENERGY consultant: Request a discussion.
Sources
- GME — PUN Index GME (accessed 10 October 2026)
- GME — Glossario (accessed 10 October 2026)
- GME — Vademecum della borsa elettrica, aggiornamento 31.01.2026 (accessed 10 October 2026)
- GME — Disposizione tecnica di funzionamento n. 11 rev. 01 ME, intervallo di tempo di mercato (accessed 10 October 2026)
- GME — Nuovo formato XSD per le offerte a blocchi e a 15 minuti, aggiornamento 01.10.2025 (accessed 10 October 2026)
- ARERA — Delibera 304/2024/R/eel, superamento del prezzo unico nazionale (accessed 10 October 2026)
- ARERA — Relazione 274/2026/I, relazione annuale ad ACER e alla Commissione europea (accessed 10 October 2026)
- MASE — Mercato elettrico, decreto 18 aprile 2024 sui prezzi zonali (accessed 10 October 2026)
- Terna — Mercato elettrico e configurazione zonale (accessed 10 October 2026)
Informational content by IPGS ENERGY. Information is reviewed as of the stated update date and does not replace a contractual, tax or regulatory assessment specific to an individual business.
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