Between 4 and 7 August, the four largest independent power producers in the United States — generators that sell electricity, capacity and grid services at wholesale prices they cannot set, with no regulator guaranteeing them a return — closed out a quarter that was, on the numbers, the best any of them has reported. Three of the four told investors the year would be better than they had previously said. Their shares sit 21% to 35% below where they traded a year ago.

What the four reported

Constellation Energy, the country's largest unregulated generator with 32,400 megawatts of nuclear, gas, wind, solar and hydro sold to utilities, municipalities and industrial customers, posted second-quarter revenue of $7.51bn, up 23%, and adjusted operating earnings of $2.55 a share, up $0.64 from a year earlier. On its 6 August call it raised 2026 guidance to $11.50–$12.50 a share from $11–$12 — the new midpoint equals the old top end. It signed roughly 920 megawatts of long-term nuclear supply contracts in the quarter at an average tenor of 18.5 years, including the first nuclear power-purchase agreement ever struck by a major retailer, taking contracted clean baseload to about 30% of the fleet. Its nuclear production tax credit strike price, an inflation-linked federal revenue floor, rose to $50.88 from $49.88 a megawatt-hour. It has bought back $2.2bn of stock this year with $2.8bn of authorisation left.

Talen Energy, a Houston-based owner of 10.7 gigawatts of nuclear, gas and coal plants whose Susquehanna nuclear station supplies an Amazon data centre, raised full-year adjusted EBITDA guidance to $2.03–$2.23bn and free cash flow to $1.20–$1.35bn. Quarterly revenue rose 64.5% to $747m and gross margin widened to 49.3% from 20.7%; the reported $92m net loss is unrealised derivative marks, not operations. It closed the 2.6-gigawatt Cornerstone acquisition on 15 June.

Vistra, an integrated retailer-generator with 38,700 megawatts and about 4.3 million retail electricity customers across 20 states, grew adjusted EBITDA 31% to $1.77bn, its generation arm up 68% to $994m on hedging and higher capacity revenue while retail held flat at $773m. Revenue fell 5.5% to $4.02bn but gross margin expanded to 23.5% from 22.0%. It reaffirmed 2026 EBITDA of $6.8–$7.6bn and held its 2027 range at $7.4–$7.8bn, conceding it is biased toward the low end; the pending Cogentrix purchase and a long-term Meta supply contract, worth roughly $700m, are excluded from that figure.

NRG Energy, which sells power to about six million customers under the Reliant, Direct Energy and Green Mountain brands and owns generation in Texas, the East and the West, is the exception. Adjusted earnings of $1.49 a share missed the $1.82 consensus by 18% and the shares fell about 9% toward a 52-week low, even though adjusted EBITDA rose 34% to $1.22bn. Its Texas segment lost $131m of EBITDA because Houston around-the-clock power cleared at $33 a megawatt-hour against a $52 planning assumption. Against that, it agreed commercial terms with an unnamed investment-grade hyperscaler for a 1.2-gigawatt gas plant, expandable to 2.4, for late-2029 service: $500m of run-rate EBITDA and $375m of free cash flow on $3.2bn of capital, structured as a fixed availability payment covering roughly 95% of the cash flow.

Verdict on the business: CONTRADICTS the decline at Constellation, Talen and Vistra; CONFIRMS it at NRG.

Two mergers hiding in the averages

A fifth name usually grouped here, AES, the diversified international generator with 31,459 megawatts across the Americas, Europe and Asia, is not a read on merchant power at all: it is being taken private for $15.00 a share in cash by a consortium led by Global Infrastructure Partners and EQT, approved by shareholders on 26 June. At $14.73 it trades 1.8% under the deal price. Its year-long gain is arbitrage arithmetic.

The same caution applies on the regulated side. Dominion Energy's steady uptrend reflects its agreed all-stock combination with NextEra Energy at 0.8138 NextEra shares per Dominion share, filed with regulators on 15 July.

Valuation

Vistra at 16.0 times forward earnings, Talen at 16.9 and NRG at 13.5 all sit below Dominion's 18.8, while consensus has Vistra growing 2027 earnings 20.6% and NRG 23.1% against Dominion's 6.4%. Constellation, at 23.8 times forward, is the only one at a premium to that anchor — and its trailing multiple fell from 41.3 times in early May to 27.1 today while the share price rose 0.8%, so earnings, not price, did that work. Verdict on valuation: CONTRADICTS the de-rating at Vistra, NRG and Talen; INCONCLUSIVE at Constellation.

The tape, and what is actually pressuring it

All four merchants have traded with their 50-day average below their 200-day since midsummer, and NRG, Vistra and Constellation sit 31% to 35% off 52-week highs against 6% to 12% for the regulated group. But the rotation is a twelve-month event, not a live one: over the past 30 days the regulated names fell slightly more than the merchants, and three of them lost their strongest uptrend readings on 7 August.

The live pressure is Texas. On 3 August the governor ordered the state's utility commission and grid operator to audit every data-centre project in an interconnection queue that has swollen past 474 gigawatts, suspending large-load notifications. Vistra executives publicly supported the pause and said it does not affect their 1.2-gigawatt Amazon contract at the Comanche Peak nuclear plant. Underneath it, ERCOT battery capacity passed 14 gigawatts by mid-2025, nearly triple early-2023 levels, with 37 gigawatts projected by end-2027, which is the mechanical reason Houston power printed $33.

The eastern grid runs the other way. PJM's 2027/28 capacity auction cleared at the approved cap of $333.44 per megawatt-day across the whole footprint, procuring 134,479 megawatts for $16.4bn — a third straight year at the ceiling, and PJM's own estimate is that it would have cleared 60% higher uncapped. The negotiated collar's last capped auction runs in December 2026 at $325, after which the cap reverts to a cost-based figure near $550. Demand, meanwhile, keeps rising: Amazon, Alphabet, Meta and Microsoft lifted combined 2026 capital spending guidance to roughly $725bn, up about 77% on 2025.

The setup

Where it stands — Three of four merchant generators raised or held 2026 guidance in August; all four trade far below last summer's prices.

Would confirm — Vistra's Q3 update lifting 2027 EBITDA above $7.8bn once Cogentrix closes, or NRG's Texas segment recovering toward its $52/MWh assumption.

Would invalidate — Vistra settling at or below the $7.4bn low end for 2027, or the Texas audit delaying signed data-centre contracts.

Watch next — PJM's December 2026 base residual auction, the final one capped at $325 per megawatt-day.

Valuation — Vistra 24.2x trailing and 16.0x forward, NRG 31.4x and 13.5x, Constellation 27.1x and 23.8x, against Dominion's 18.8x forward.