As the California Independent System Operator (CAISO) finalizes preparations for one of the most significant wholesale market transformations in a generation, market participants across the Western United States are preparing for EDAM (Extended Day-Ahead Market) and DAME (Day-Ahead Market Enhancements).

Building on the foundational overview from our first ISO Market Edge Newsletter edition, this update provides deeper insight into upcoming milestones, market participants, timelines, participant readiness expectations, and strategic actions.

Launching May 1, 2026, EDAM expands day-ahead market participation across the Western Energy Imbalance Market, enabling greater regional coordination, improved reliability, and more efficient resource optimization. Complementing this, DAME enhances CAISO’s internal market design by introducing new reserve and reliability products to better manage uncertainty and grid variability. Together, these reforms support a more integrated, resilient, and cost-effective Western power system.

The Southwest Power Pool (SPP) is preparing for one of the most significant market expansions in North America. On April 1, 2026, most participants in the Western Energy Imbalance Service will transition into SPP’s Integrated Marketplace, gaining full regional transmission organization (RTO) services and broader market access. This expansion positions SPP as the first U.S. RTO to operate across both the Eastern and Western Interconnections, enabling more coordinated operations, enhanced reliability, and long-term economic efficiencies across a larger regional footprint.