Midcontinent Independent System Operator, Inc.; AEP Indiana Michigan Transmission Company, Inc.; ALLETE, Inc.; Ameren Illinois Company; Ameren Transmission Company of Illinois; American Transmission Company, LLC; Cleco Power LLC; Duke Energy Indiana, LLC; Entergy Arkansas, LLC; Entergy Louisiana, LLC; Entergy Mississippi, LLC; Entergy New Orleans, LLC; Entergy Texas, Inc.; GridLiance Heartland LLC; Indianapolis Power & Light Company; International Transmission Company; ITC Midwest LLC; Michigan Electric Transmission Company, LLC; MidAmerican Energy Company; Montana-Dakota Utilities Company; Northern Indiana Public Service Company LLC; Northern States Power Company, a Minnesota Corporation; Northern States Power Company, a Wisconsin Corporation; Northwestern Wisconsin Electric Company; Otter Tail Power Company; Pioneer Transmission, LLC; Republic Transmission, LLC; Southern Indiana Gas & Electric Company; Union Electric Company; Wabash Valley Power Association, Inc.; Wolverine Power Supply Cooperative, Inc.; Notice of Institution of Section 206 Proceeding and Refund Effective Date

Document Headings Document headings vary by document type but may contain the following: the agency or agencies that issued and signed a document the number of the CFR title and the number of each part the document amends, proposes to amend, or is directly related to the agency docket number / agency internal file number the RIN which identifies each regulatory action listed in the Unified Agenda of Federal Regulatory and Deregulatory Actions See the Document Drafting Handbook for more details. Department of Energy Federal Energy Regulatory Commission [Docket No. EL26-70-000] On June 18, 2026, the Commission issued an order in Docket No. EL26-70-000 pursuant to section 206 of the Federal Power Act (FPA), 16 U.S.C. 824e , instituting an investigation to determine whether Midcontinent Independent System Operator, Inc.'s Open Access Transmission, Energy, and Operating Reserve Markets Tariff is unjust, unreasonable, unduly discriminatory or preferential, or otherwise unlawful. Midcontinent Indep. Sys. Operator, Inc., 195 FERC ¶ 61,212 (2026). The refund effective date in Docket No. EL26-70-000, established pursuant to section 206(b) of the FPA, will be the date of publication of this notice in the Federal Register . Any interested person desiring to be heard in Docket No. EL26-70-000 must file a notice of intervention or motion to intervene, as appropriate, with the Federal Energy Regulatory Commission, in accordance with Rule 214 of the Commission's Rules of Practice and Procedure, 18 CFR 385.214 (2025), within 21 days of the date of issuance of the order. In addition to publishing the full text of this document in the Federal Register , the Commission provides all interested persons an opportunity to view and/or print the contents of this document via the internet through the Commission's Home Page ( http://www.ferc.gov ) using the “eLibrary” link. Enter the docket number excluding the last three digits in the docket number field to access the …