Vistra Corp.

An evaluation was performed under the supervision and with the participation of our management, including the principal executive officer and principal financial officer, of the effectiveness of the design and operation of the disclosure controls and procedures (as such term is defined in Rules 13a-15(e) and 15d-15(e) of the Exchange Act) in effect at September 30, 2025. Based on the evaluation performed, our principal executive officer and principal financial officer concluded that the disclosure controls and procedures were effective as of that date.

During the third quarter of 2025, we completed the implementation of a new Enterprise Resource Planning (ERP) system, replacing our previous core financial system. The implementation resulted in significant changes to our processes, procedures, and controls which represents a material change to our internal control over financial reporting (ICFR). Management believes the new ERP system will strengthen our overall control environment. The Company will continue to evaluate and monitor the internal controls over financial reporting during this period of change and will continue to evaluate the operating effectiveness of related key controls. Except for the ERP implementation described above, there were no other changes in our ICFR (as such term is defined in Rules 13a-15(f) and 15d-15(f) of the Exchange Act) during the most recently completed fiscal quarter that have materially affected, or are reasonably likely to materially affect, our ICFR.