Commonwealth Fusion Systems

Fusion energy company developing SPARC, a compact tokamak powered by high-temperature superconducting magnets 40× stronger than conventional designs. Raised $1.84B in 2021 (led by Tiger Global, Salesforce Ventures, Breakthrough Energy); demonstrated 20-tesla magnet world record in Sep 2021. On track to demonstrate net-energy fusion by 2025 and deploy ARC commercial power plant by 2030s.

Climate🇺🇸 United StatesFounded 2018ISO/NSO equitycfs.energy ↗

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Reviewed May 24, 2026 (2d ago)

Current estimate

4 methods · May 24, 2026Medium confidence (36%)

$2.9B

range $1.9B – $3.9B⚠ methods disagree (38.2× spread)

Implied per-share: $10.5 · vs last primary +13%

This estimate reflects what informed investors are paying on secondary markets like Hiive and Forge — not the 409A valuation on your grant letter.

Last primary round

$2.6B

Series B · 54mo ago

Secondary signal

$2.9B

Forge · 2026-04+13%

Sourced from Forge/Hiive public data. Full order books require a paid subscription; figures shown are best-effort from public disclosures.

Headcount

800

employees · LinkedIn+23%

LinkedIn count — directional proxy only. Historical figure sourced via Wayback Machine; treat ±15% as normal variance.

Revenue (est.)

$12M

annual run rate · est.

Complete company data

Every input we use, where we got it from, and how much we trust it.

Field	Value	Source	Confidence
Company fundamentals
Sector	Climate	Editorial classification	high
Headquarters	🇺🇸 United States	Company website · Crunchbase	high
Founded	2018	Company website · Wikipedia	high
Website	cfs.energy	Direct	high
Latest primary round
Post-money valuation	$2.6B	Bloomberg Dec 2021	high
Round name	Series B	Bloomberg Dec 2021	high
Date	2021-12-01 (54 months ago)	Bloomberg Dec 2021	high
Lead investor	Tiger Global / Salesforce Ventures / Breakthrough Energy	Bloomberg Dec 2021	high
Amount raised	$1.8B	Bloomberg Dec 2021	medium
Capitalization
Total fully-diluted shares	280M	SEC Form D · secondary price math · cap-table leaks › notes Public total fully-diluted share count: estimated from SEC Form D filings, secondary-market pricing math (implied valuation ÷ price per share), and leaked cap-table summaries. Considered the lowest-confidence input.	low
Implied share price (latest primary)	$11	Valuation × 1000 / share count (= $2.6B ÷ 280M)	medium
Primary equity type granted	ISO/NSO	Public reports of company equity practices	high
Financials
Annual revenue (est.)	$12M	Sacra · The Information · press leaks › notes Annual revenue: best public estimates from Sacra, The Information, WSJ leaks, or company-stated ARR. Where official, we cite the source on the funding round.	medium
EV / Revenue (implied)	216.7x	Computed from valuation ÷ revenue	medium
Headcount
Employees (now)	800	LinkedIn — current company page count › notes Headcount: LinkedIn 'Company' page employee count, taken now and approximately 12 months ago via the Wayback Machine. Treat as a directional proxy for revenue growth, not a hard number.	medium
Employees (12 months ago)	650	LinkedIn via Wayback Machine	medium
12-month headcount growth	+23%	Computed	medium
Methodology inputs
Sector ETF proxy	ICLN	Editorial choice — most representative public ETF › notes Sector ETF: editorial choice of the most representative public-market proxy. Annual return: 3-year trailing average from Yahoo Finance, refreshed quarterly.	medium
ETF annual return (trailing 3-yr)	8%	Yahoo Finance · refreshed quarterly	medium

Funding history

Primary rounds reported in Bloomberg, WSJ, TechCrunch, Reuters, or SEC Form D filings (efts.sec.gov). Linked per round below.

Valuation progression (equity rounds)

Valuation progression · equity rounds

$2.6Blatest · Series B

Total growth

17×

Our estimate

$2.9B

Primary round

Down round

Our estimate

Series B+420%2021-12-01

$2.6B

Led by Tiger Global / Salesforce Ventures / Breakthrough Energy · raised $1.8B

Source: Bloomberg Dec 2021

Series A+233%2018-09-01

$0.5B

Led by Khosla Ventures / Breakthrough Energy · raised $115M

Source: TechCrunch Sep 2018

Seed2018-03-01

$0.2B

Led by The Engine (MIT) · raised $29M

Source: MIT News

Secondary market signals

Secondary market signals: bid/ask/trade indications from Hiive (hiive.com), Forge Global, Caplight Index, and tender prices reported in the press.

Implied valuation over time

Implied valuation · secondary market

$2.9B+5% vs first recorded

Trade

⚠

Forge and Hiive publish aggregated market data publicly, but full order books, individual bids/asks, and confirmed trade prices require a paid account. The figures below are sourced from their public summaries, press-reported tender prices, and SEC disclosures. They represent the best publicly available signal — not a guaranteed executable price.

Date	Type	Source	Price / share	Implied valuation
2026-04-16	trade	Forge	$11	$2.9B
2026-02-08	trade	Hiive	$10	$2.8B

View live indications: Hiive ↗ · SEC Form D filings ↗

Public peer comparables

Public peer comparables: editorial selection of public companies with the closest business model. EV/Revenue and growth from public 10-Q filings and Bloomberg, refreshed quarterly.

Ticker	Company	EV / Revenue	Revenue growth	As of
CWEN	Clearway Energy, Inc.	6.3x	+19%	2026-05-24
ENPH	Enphase Energy, Inc.	6.03x	+-21%	2026-05-24
FSLR	First Solar, Inc.	5.11x	+24%	2026-05-24
NEE	NextEra Energy, Inc.	6.63x	+7%	2026-05-24

Confidence breakdown

How much we trust each of the four valuation methods for this specific company, and why.

Method A — Peer-multiple

weight 25%→ $0.0B23% confidence

↳ Effectively excluded from the blend — this method is structurally unreliable for this company.

Growth-weighted peer EV/Revenue: 5.6x → 35% private-company discount → 3.6x on $12M revenue. Output implies less than half the recent market anchor ($3B) — this company is likely valued on optionality / non-revenue factors and Method A is structurally less reliable here.

Method B — Secondary-implied

weight 45%→ $2.9B55% confidence

Recency-weighted average of 2 secondary indications (180-day decay)

Method C — Primary time-decay

weight 20%→ $3.8B20% confidence

↳ Effectively excluded from the blend — this method is structurally unreliable for this company.

$2.6B round (2021-12-01) × 2.26× growth × 0.85× multiple decay over 4.5 years — capped at 1.3× recent secondary ($2.9B → $3.8B)

Method D — Sector momentum

weight 10%→ $3.7B10% confidence

↳ Effectively excluded from the blend — this method is structurally unreliable for this company.

$2.6B × (1 + 8% p.j.)^4.5yr = $3.7B via ICLN ETF-proxy

Overall confidence

36%

Weighted average of the four methods. Above 65% is high, 40–65% medium, below 40% low.

Medium

Worked example for an employee

A concrete walk-through using a hypothetical employee profile. Same engine the calculator uses — try it with your real numbers.

Profile: a hypothetical employee who joined Commonwealth Fusion Systems 24 months ago (2024-05-26) with 2,000 options, on the standard 4-year vesting schedule with a 1-year cliff.

Vesting

1,000 of 2,000

50% vested at month 24

Implied share price (mid)

$11

weighted average of 4 methods

Gross vested value

$10,511

vested shares × implied price

Net value

$10,511

no strike, gross = net

Tax (rough)

$1,051

US federal only · AMT risk: low

What if the next round is…

Up round +30%

$11,882

New round at +30% valuation, 15% new shares issued

Down round −30%

$6,131

New round at −30% valuation, 20% new shares (higher dilution in distress)

Secondary today

$8,934

Sale on the secondary market at the typical 15% discount to the mid estimate

These numbers come from the same engine as the live calculator. Walk through with your own grant: use your real numbers →

Transparent assumptions

What we assumed where exact data isn't available. If any of these don't match your situation, the numbers above will be off.

Fully-diluted share count

280M shares

We don't have authoritative cap-table access for private companies. The number above is reconstructed from SEC Form D filings, secondary-market price-vs-valuation math, and leaked share-class summaries. Actual fully-diluted count (including unvested option pool and SAFEs) may differ by 5–15%.

Common-stock waterfall

1.0× to common

We assume a clean common-stock outcome — i.e. preferred-share liquidation preferences and ratchets do not extract value before common. In a down-exit, this assumption can be very wrong: preferred stack can take 30–70% of proceeds.

Private-company illiquidity discount

35% off public peers

Applied to Method A (peer-multiple). Per-company because category leaders with deep secondary markets and a clear IPO path warrant a smaller discount than early-stage names. The literature range is 10–35%; for Commonwealth Fusion Systems we use 35% based on secondary-market depth, valuation history, and proximity to liquidity.

Revenue growth assumption (Method C)

20% YoY

Compounded forward from the last primary date to today to estimate the company's value drift. Set per-company based on disclosed or reported ARR trajectory. Method C is further capped at 1.3× the most recent secondary trade (if any) to stop runaway extrapolation when revenue growth outpaces what the market is actually paying.

Sector ETF momentum (Method D)

ICLN @ 8%/year

Method D applies the trailing return of ICLN as a market-proxy adjustment to the primary valuation. Crude — meant as a tiebreaker when peer and secondary data conflict, not as a primary signal.

Outlier auto-downweight

Methods >50% from median get ½ weight

Robust-statistics safety net: any method whose output strays more than 50% from the median of the other three methods has its confidence weight halved when computing the blended mid-point. Prevents a single bad extrapolation from dragging the headline.

Recency decay for secondary trades

180-day half-life (e⁻ᵈ/¹⁸⁰)

A trade from 30 days ago counts ~5× more than one from 180 days ago. Tunable; some platforms use shorter half-lives.

Tax estimate

US federal only, single filer

Uses 2024 US federal brackets, ignoring state tax, NIIT, AMT credit recovery, and any other deductions. Treat as a directional sanity check, not a tax bill.

All data from public sources. Not investment, tax, or legal advice. Not affiliated with Commonwealth Fusion Systems. Last refreshed manually — see methodology for our update cadence.