OMIE launches daily day-ahead price spread index for Iberian market

OMIE began publishing, since mid-August 2026, a new daily indicator on its public 'SPOT hoy' section showing the arithmetic price spread between the highest- and lowest-priced quarter-hourly periods of the day-ahead market, for both Spain and Portugal, calculated over 1, 2 and 4-hour windows (4, 8 and 16 quarter-hour periods) with both 'consecutive' and 'non-consecutive' period calculation options.

The new indicator increases market transparency by giving participants and the public a simple daily reference for intraday price arbitrage potential in the day-ahead market, which is increasingly relevant given rising renewable penetration and growing use of flexibility resources such as storage and demand response that respond to price signals.

This is a market-data/transparency enhancement rather than a rule change: OMIE, as the designated NEMO for the Iberian day-ahead and intraday markets, is adding a derived analytics product (a price-spread index) built on existing quarter-hourly day-ahead settlement prices for Spain and Portugal. It does not alter market coupling, bidding, or clearing mechanics, but it operationalizes a clearer signal of intraday price volatility/arbitrage potential, which can influence storage and demand-response dispatch decisions and bidding strategies without requiring any regulatory approval or market rule amendment. Because it is purely an informational publication (available retroactively for a rolling year and updated daily), it is already fully live with no further regulatory or implementation milestones indicated.

OMIE market operator publication (NEMO transparency initiative); no specific regulatory framework cited

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