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The ISOʼs regional market offerings provide platforms for day-ahead and real-time energy trading for participants across the West.

Western Energy Markets

ISO 2025 Year in Review: Powering forward on reliability, shared progress, and a new framework for independent market governance

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WEIM Q3 Benefits Report
$412 million
Savings in Q3 2025
$7.82 billion
Total gross benefits since Nov 2014

The WEIM AT 10 YEARS

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The western energy markets encompass the Western Energy Imbalance Market (WEIM) and the Extended Day-Ahead Market (EDAM). Developed in partnership with stakeholders from across the West, these markets have been designed to reflect and respect the region's diversity.

A west-wide energy market is essential for the efficient and reliable distribution of electricity across the West. Coordinated management of diverse resources across a broad footprint has led to substantial cost savings to customers, improved reliability, and significant environmental benefits.

WEIM

The Western Energy Imbalance Market is a stand-alone market platform for balancing authorities in the West, enabling real-time balancing of supply and demand leveraging the diverse resources in the region. Since its launch in 2014, WEIM has expanded to include 21 balancing authorities outside of the ISO across 11 western states.

Learn more about WEIM

EDAM

Set to launch in 2026, the Extended Day-Ahead Market extends market operations into the day-ahead timeframe. Available to entities participating in WEIM, EDAM will assist balancing authorities in the West in pre-positioning supply to meet forecasted electric demand for the following day.

Learn more about EDAM

News & Notices

See the latest developments in the Western Energy Markets and subscribe for news releases and notices.