Material Event (Form 8-K)

On September 29, 2025, Vistra Corp. ("Vistra" or the "Company") announced that it has entered into a 20-yearpower purchase agreement (with options to extend for up to an additional 20 years) (the "PPA") with a large, investment grade company (the "Customer"), pursuant to which the Company has agreed to supply to the Customer 1,200 MW of carbon-free power from the Comanche Peak Nuclear Power Plant. Vistra anticipates power delivery to begin in the fourth quarter of 2027 and ramp to full capacity by 2032. Assuming forwards as of Aug. 29, 2025, an Adjusted EBITDA Midpoint Opportunity consistent with Vistra's previously communicated fiscal year 2026 expectation, and Vistra's medium-term expected conversion ratio of Adjusted Free Cash Flow before Growth to Adjusted EBITDA, Vistra expects incremental Adjusted Free Cash Flow before Growth accretion to be in the range of approximately 8-10%if the Customer utilizes the full capacity.

About Vistra

Vistra (NYSE: VST) is a leading Fortune 500 integrated retail electricity and power generation company based in Irving, Texas, that provides essential resources to customers, businesses, and communities from California to Maine. Vistra is a leader in transforming the energy landscape, with an unyielding focus on reliability, affordability, and sustainability. The company safely operates a reliable, efficient power generation fleet of natural gas, nuclear, coal, solar, and battery energy storage facilities while taking an innovative, customer-centric approach to its retail business. Learn more at vistracorp.com.