NOTICE DATE: November 10, 2026

NOTICE TYPE: M-C111126-01 Operations

SHORT DESCRIPTION:  Potential Price Correction - Incorrect Consideration of Ancillary Service Only Offers in Day-Ahead Market

INTENDED AUDIENCE: All Market Participants

DAYS AFFECTED: November 1, 2026

LONG DESCRIPTION: ERCOT identified a software defect that affected the Day-Ahead Market (DAM) for Operating Day (OD) November 1, 2026. This defect prevented some Ancillary Service Only Offers after the Daylight Saving Time transition from consideration in the DAM. ERCOT has corrected the affected input data, and a permanent software fix is planned for future release.

Under ERCOT Protocol Section 4.5.3(6)(a), ERCOT must notify Market Participants within 30 days of an OD if it determines that DAM prices meet the criteria for correction and ERCOT Board review. This Market Notice is intended to notify Market Participants of the potential ERCOT Board review of DAM prices for OD November 1, 2026.

ERCOT will issue a follow-up Market Notice with the results of its analysis and whether it will seek ERCOT Board review.

CONTACT: If you have any questions, please contact your ERCOT Account Manager. You may also call the general ERCOT Client Services phone number at (512) 248-3900 or contact ERCOT Client Services via email at ClientServices@ercot.com.

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