NOTICE DATE: May 20, 2026

NOTICE TYPE: M-A052026-01 Operations

SHORT DESCRIPTION: Potential Price Correction - Incorrect consideration of ECRS Ramp Rate Telemetry for Non-Controllable Load Resources.

INTENDED AUDIENCE: All Market Participants

DAYS AFFECTED: Apr 29, 2026 - May 19, 2026

LONG DESCRIPTION: ERCOT identified a software defect that incorrectly set the ERCOT Contingency Reserve Service (ECRS) Ramp Rate telemetry to zero during input validation for Non-Controllable Load Resources (NCLR) and excluded some NCLRs from receiving ECRS awards. The defect affected multiple Security-Constrained Economic Dispatch (SCED) intervals across Operating Days (OD) April 29, 2026 through May 19, 2026. ERCOT corrected the defect on May 19, 2026.

Under ERCOT Protocol Section 6.3(7)(a), ERCOT must notify Market Participants within 30 days of an Operating Day if it determines that prices meet the criteria for correction and ERCOT Board review. This Market Notice preserves the eligibility of the ERCOT Board to review prices for the affected Operating Days that are within 30 days of this notice.

ERCOT continues to investigate how the error affected Real-Time Market prices. ERCOT will issue a follow-up Market Notice with 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.

If you are receiving email from a public ERCOT distribution list that you no longer wish to receive, please follow this link in order to unsubscribe from this list: http://lists.ercot.com.

dg