Vistra, 424B5 증권신고서 제출: 투자설명서(424B)

SUBJECT TO COMPLETION, DATED SEPTEMBER 10, 2026

The information in this preliminary prospectus supplement is not complete and may be changed. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell these securities, and we are not soliciting an offer to buy these securities, in any jurisdiction where the offer or sale is not permitted.

PRELIMINARY PROSPECTUS SUPPLEMENT (To Prospectus dated September 8, 2026)

Vistra Operations Company LLC

$ % Series A Junior Subordinated Notes due 2057

$ % Series B Junior Subordinated Notes due 2057 irrevocably and unconditionally guaranteed by Vistra Corp.

Vistra Operations Company LLC (“Vistra Operations”) is offering $ aggregate principal amount of notes, consisting of $ aggregate principal amount of % Series A Junior Subordinated Notes due 2057, or the “Series A Junior Subordinated Notes,” and $ aggregate principal amount of % Series B Junior Subordinated Notes due 2057, or the “Series B Junior Subordinated Notes.” We refer to the Series A Junior Subordinated Notes and the Series B Junior Subordinated Notes collectively as the “notes.” The notes will be irrevocably and unconditionally guaranteed by Vistra Corp. Each series of the notes is being offered under the Subordinated Indenture (as defined below).

The Series A Junior Subordinated Notes will bear interest (i) from and including , 2026 (which is the expected original issuance date) to, but excluding, March 15, 2032 (the “First Series A Reset Date”) at the rate of % per year and (ii) from and including the First Series A Reset Date, during each Reset Period (as defined herein), at a rate per year equal to the Five-year U.S. Treasury Rate (as defined herein) as of the most recent Reset Interest Determination Date (as defined herein) plus a spread of %, to be reset on each Series A Reset Date (as defined herein); provided, that the interest rate during any Reset Period will not reset below % (which equals the initial interest rate on the Series A Junior Subordinated Notes).

The Series B Junior Subordinated Notes will bear interest (i) from and including , 2026 (which is the expected original issuance date) to, but excluding, March 15, 2037 (the “First Series B Reset Date”) at the rate of % per year and (ii) from and including the First Series B Reset Date, during each Reset Period, at a rate per year equal to the Five-year U.S. Treasury Rate as of the most recent Reset Interest Determination Date plus a spread of %, to be reset on each Series B Reset Date (as defined herein); provided, that the interest rate during any Reset Period will not reset below % (which equals the initial interest rate on the Series B Junior Subordinated Notes).

Subject to its right to defer interest payments as described below, Vistra Operations will pay interest on each series of notes semi-annually in arrears on March 15 and September 15 of each year, beginning March 15, 2027. Each series of notes will mature on March 15, 2057.

Vistra Operations may defer interest payments on either or both series of the notes on one or more occasions for up to 10 consecutive years per deferral period as described in this prospectus supplement. Deferred interest payments with respect to a given series of the notes will accumulate additional interest at a rate equal to the interest rate then applicable to that series of notes, to the extent permitted by law.

Vistra Operations may elect to redeem any or all of the notes at the times and prices specified in this prospectus supplement plus accrued and unpaid interest to the redemption date. The redemption prices are described beginning on page S- 25 of this prospectus supplement.