Purchasing in MIBEL intraday markets

The MIBEL intraday markets are the operational adjustment layer between OMIE day-ahead and the REE balancing platforms. They exist because no day-ahead forecast is perfect: weather changes, demand surprises arrive, generators have unplanned outages, and the positions need adjusting before delivery.

For a retailer, the intraday markets are both the safety net that absorbs forecast error and the opportunity layer that can capture price swings. Most retailers use them defensively. The ones that treat them as a deliberate trading workflow do meaningfully better.

The market structure

MIBEL intraday has two parts:

The intraday auctions. Six discrete auctions through the day, each clearing a window of hours ahead of physical delivery. The auctions follow the same pay-as-clear mechanic as OMIE day-ahead. The format is documented, the clearing is published, and the counterparty exposure is the same as day-ahead.

The continuous intraday market. A continuous-trading platform where participants can adjust positions up to roughly an hour before physical delivery. The clearing is bilateral against the order book. The platform is operated under the SIDC (Single Intraday Coupling) European framework.

A retailer can use either or both, depending on the size of the position adjustment and the price signals.

Patterns that matter

The auctions have predictable liquidity. The first auction of the day (covering hours 04:00-23:00 of the delivery day) is the most liquid. The later auctions are thinner. A retailer covering a significant intraday position should use the first auction in preference where it can.

Continuous intraday clears with persistent spread. The bid-offer spread on the continuous platform widens materially in the off-peak hours and tightens during the peak. A retailer with a large position to cover in an off-peak hour either pays the spread or splits the position across multiple smaller trades.

Cross-border interconnection capacity matters. The continuous intraday platform is European; capacity flows between Iberia, France and Northern Europe affect the clearing. A position in Iberia at a time of constrained interconnection capacity to France clears at a different price than the same position when capacity is open.

Imbalance settlement is the alternative. A retailer that does not adjust a position in intraday settles the imbalance against REE's balancing market, at a price that is systematically penal to the imbalanced party. The decision between intraday adjustment and accepting imbalance settlement is an explicit commercial decision the desk should be making, not a default.

What goes wrong

Three failure patterns turn up regularly.

The intraday workflow runs from the same data as the day-ahead workflow. If the forecast that drove the day-ahead bid has not been updated, the intraday adjustment uses the same wrong forecast. The forecast needs a refresh cadence aligned to the intraday auction schedule.

Position visibility is poor. A retailer that does not have a clear view of its current position by hour cannot make intelligent intraday adjustments. Most retailers under 1 TWh are running this on a spreadsheet that is updated once a day.

The continuous market is treated as too complex to touch. Most retailers under 1 TWh do not participate in continuous intraday at all, accepting the imbalance settlement cost instead. For some books this is a defensible position; for many it is leaving margin on the table.

How this lands in the operating model

A working intraday desk has three components:

An intraday forecast refresh that updates after the OMIE day-ahead clears and refreshes again before each intraday auction.
A position-tracking layer that gives the desk a real-time view of the current position by hour against the demand forecast.
A decision framework that defines, for each intraday auction and continuous trade, whether the desk should adjust or accept imbalance.

This is operational work, not a system replatform. The purchasing pillar covers it as a 4 to 8 week engagement layered on top of the day-ahead operations.