⚠ Fifteen Per Cent of the Fleet Carries the StoryHigh threat

Vistra (VST) — threat to the moat

The other 85% earns what merchant generation earns, which is what the 2021 and 2022 returns record.

Nuclear is 6,448 megawatts of roughly 44,0001 — under 15% of the fleet. Every argument about irreplaceability applies to that slice and to nothing else.

Fleet split (MW)~37,552 MWEverything a rival can buy6,448 MWNuclearThe other 85% earns merchant spreads set by whichever unit is marginal in the hour
Every irreplaceability argument applies to the smaller bar. The larger one produced the 2021 and 2022 return figures.

The rest earns what merchant generation earns: the spread between the power price and the fuel cost, set by whichever unit is marginal in the hour, competed against every other owner of similar plant. When ERCOT is short, that is a very good business. When it is not, it is a business with high fixed costs and no pricing power at all, which is what the 2021 and 2022 return-on-capital figures record.

There is a subtler problem in the coal fleet specifically. Eight thousand seven hundred and forty-three megawatts of coal and lignite2 is a large position in an asset class that carries carbon exposure, retirement dates and remediation obligations, and whose current value comes almost entirely from the grid being tight. Vistra's plan to repower two of them as gas plants3 is the right answer and it is a capital cost rather than a windfall.

The measure that matters is what share of Adjusted EBITDA comes from contracted or nuclear output rather than from merchant spreads. Vistra does not report it that way. As the Amazon and Meta contracts begin delivering it will become visible in the segment results, and it is the single best indicator of whether the moat is spreading beyond that 15%.

References
  1. Moat Explorer calcNuclear is 6,448 megawatts of roughly 44,000 — under 15% of the fleet
    Vistra Corp. Form 10-K, FY2025, Item 2 Properties and generation fleet — six nuclear generating units at four facilities totalling 6,448 MW: Comanche Peak Unit 1 (ERCOT, 1,200 MW, 18-month refuelling, licence to 2050), Comanche Peak Unit 2 (ERCOT, 1,200 MW, 2053), Beaver Valley Unit 1 (PJM, 939 MW, 2036), Beaver Valley Unit 2 (PJM, 933 MW, 2047), Perry (PJM, 1,268 MW, 24-month refuelling, 2046) and Davis-Besse (PJM, 908 MW, 24-month refuelling, 2037), with nuclear units "generally operated at full capacity"; coal and lignite fleet of seven facilities totalling 8,743 MW; twelve peaking generation facilities totalling 4,822 MW; battery energy storage of 350 MW in California, 270 MW in Texas and 4 MW in Illinois; solar of 538 MW in Texas and 112 MW in Illinois; the Moss Landing 100 MW and 300 MW battery facilities "will not return to service" — FY2025 · publ. February 2026 · source ↗
  2. ReportedEight thousand seven hundred and forty-three megawatts of coal and lignite is a large position in an asset class that carries carbon exposure, retirement dates and remediation obligations, and whose current value comes almost...
    Vistra Corp. Form 10-K, FY2025, Item 2 Properties and generation fleet — six nuclear generating units at four facilities totalling 6,448 MW: Comanche Peak Unit 1 (ERCOT, 1,200 MW, 18-month refuelling, licence to 2050), Comanche Peak Unit 2 (ERCOT, 1,200 MW, 2053), Beaver Valley Unit 1 (PJM, 939 MW, 2036), Beaver Valley Unit 2 (PJM, 933 MW, 2047), Perry (PJM, 1,268 MW, 24-month refuelling, 2046) and Davis-Besse (PJM, 908 MW, 24-month refuelling, 2037), with nuclear units "generally operated at full capacity"; coal and lignite fleet of seven facilities totalling 8,743 MW; twelve peaking generation facilities totalling 4,822 MW; battery energy storage of 350 MW in California, 270 MW in Texas and 4 MW in Illinois; solar of 538 MW in Texas and 112 MW in Illinois; the Moss Landing 100 MW and 300 MW battery facilities "will not return to service" — FY2025 · publ. February 2026 · source ↗
  3. ReportedVistra's plan to repower two of them as gas plants is the right answer and it is a capital cost rather than a windfall
    Vistra Corp. Form 10-K, FY2025, growth and portfolio transformation — acquisition of Energy Harbor in 2024 "including 4,048 MW of nuclear generation facilities in PJM"; acquisition in 2025 of 2,557 MW of natural gas generation facilities in Delaware and Pennsylvania (PJM), Rhode Island (ISO-NE), New York (NYISO) and California (CAISO); plans to add 433 MW of uprate capacity from the Perry, Davis-Besse and Beaver Valley nuclear plants in PJM; announced plans "to repower the Coleto Creek and Miami Fort coal generation facilities as natural gas-fueled facilities upon their retirement no later than 2027 and the middle of 2028, respectively"; commercial operations reached at the Oak Hill solar facility in Texas totalling 200 MW; twenty-year PPAs with Meta for a total of 2,609 MW of carbon-free power and capacity from the PJM nuclear plants, with delivery commencing on a portion of operating energy and capacity in late 2026 and full delivery by year end 2027, and uprate delivery commencing in 2031 with full delivery by year end 2034 — FY2025 · publ. February 2026 · source ↗
Sources
Generated September 23, 2026