Fundraising Fox

Helion Energy

YC S14

Seattle, US · Founded 2013 · Delaware corporation · 150 employees · 12 known investors

Helion develops fusion energy systems designed to generate clean electricity for commercial use. The company builds pulsed magnetic fusion prototypes with applications for industrial and commercial electricity generation.

Also known as Helion

Advanced ManufacturingCleantechClimate TechDeep TechEnergyHardwareFusion EnergyHard TechClimateUnited States of AmericaAmerica / Canada

Founders & leadership· Y Combinator alumni (S14)

DKDavid Kirtley
David Kirtleyin𝕏Founder and CEOFounder and CEO of Helion Energy, a privately funded company developing fusion energy systems—pulsed magnetic fusion prototypes—to generate clean electricity for commercial and industrial use.
CPChris Pihl
Chris PihlinCo-Founder, CTOCo-founder and CTO of Helion Energy, which develops pulsed magnetic fusion systems to generate electricity for commercial and industrial use.
JS
John SloughCo-Founder & Chief Scientistformer
GVGeorge Votroubek
George VotroubekinCo-founder and Chief Scientist of Helion Energy, which develops pulsed magnetic fusion systems for commercial and industrial electricity generation.
AP
Anthony PancottiinCo-founderCo-founder of Helion Energy, which develops pulsed magnetic fusion prototypes aimed at generating clean electricity for industrial and commercial use.
DD
Dr. David KirtleyCo-founder & CEO
DG
Dr. George VotroubekCo-Founder & Chief Scientist
DJ
Dr. John SloughCo-founder

Board

SASam Altman
Sam Altman𝕏Board directorCo-founder & CEO of OpenAI; former President of Y Combinator
ARAjay Royan
Ajay RoyaninBoard directorInvestor at Mithril Capital Management

Investors · 12

AntiSan Juan · $250K – $30M
Congruent VenturesSan Francisco · $100K – $5M
SoftBank GroupTokyo
SoftBank Vision FundLondon
Y CombinatorSan Francisco · $500K
Capricorn Investment Groupreported · 2 sourcesNew York
Lightspeed Venture PartnersreportedMenlo Park · $1.7M – $87M
Mithril Capital Managementreported · 3 sourcesAustinvia Ajay Royan · board
Sam Altmanreported
Thrive CapitalreportedNew York · $500K – $25M

Also in the syndicate · 2

NucorSoftBank Vision Fund 2

Funding

SEC filings, press & company announcements

$477.1M disclosed across 3 of 6 rounds · 2014–2026

▶$10.6MraisedJul 2015 · 6 investors · Other
Rule 506(b)
Officers, directors & promoters on the filing
  • John SloughExecutive Officer, Director
  • Christopher PihlExecutive Officer, Director
  • Sam AltmanDirector
  • Ajay RoyanDirector
  • David KirtleyExecutive Officer, Director
Offering amount
$21.2M
Amount sold
$10.6M
First sale
Jun 2015
Incorporated
Corporation, Delaware, 2013
Federal exemptions
06b
Full filing on SEC EDGAR ↗
▶$1.5MraisedAug 2014 · 3 investors · Other
Rule 506(b)
Officers, directors & promoters on the filing
  • Christopher PihlExecutive Officer, Director
  • John SloughExecutive Officer, Director
  • Ajay RoyanDirector
  • David KirtleyExecutive Officer, Director
Offering amount
$1.5M
Amount sold
$1.5M
First sale
Jul 2014
Incorporated
Corporation, Delaware, 2013
Federal exemptions
06b
Full filing on SEC EDGAR ↗

Source: SEC EDGAR Form D. Amounts as filed; amended filings shown once at their latest values.

Competitors · 1

by search overlap
F132 shared keywordsFuse Energy develops fusion energy technology, with work spanning hardened electronics and radiation testing (HEART) and recycling of radioactive waste, aiming to provide an on-demand clean energy source. It brings together a team across engineering, fusion science, energy policy, and manufacturing.

Companies competing with Helion Energy for the same Google search keywords, organic and paid, via search-intersection analysis.

In the news

Helion Energy - Wikipediaen.wikipedia.org · Aug 2026Fusion roundup: Helion sets temperature record; Inertia raises $450M -- ANS / Nuclear Newswireans.org · Jul 2026Fusion Energy Attracts $4.5 Billion in a Year; General Fusion Surges on Second Day of Nasdaq Trading — BigGo Financefinance.biggo.com · Jul 2026Helion Energy Raises $425 Million to Build World's First Nuclear Fusion Power Plant - London Dailylondondaily.com · Jul 2026Helion's $465M Raise: Inside the Fusion Energy Betangelinvestorsnetwork.com · Jun 2026Helion Energy Funding Soars to $15.5 Billion: Inside the Series G Reshaping Nuclear Fusionentrepreneurloop.com · Jun 2026Helion Raises $465 million in Latest Funding Roundthefusionreport.substack.com · Jun 2026Helion, the Sam Altman-backed fusion startup, raises $465M to build a power plant for Microsoft | TechCrunchtechcrunch.com · Jun 2026

Frequently asked questions

What does Helion Energy do?
Helion develops fusion energy systems designed to generate clean electricity for commercial use. The company builds pulsed magnetic fusion prototypes with applications for industrial and commercial electricity generation.
Who founded Helion Energy?
Helion Energy was founded by David Kirtley, Chris Pihl, John Slough, George Votroubek, Anthony Pancotti, Dr. David Kirtley, Dr. George Votroubek, Dr. John Slough in 2013.
Who are Helion Energy's investors?
Helion Energy's investors include Anti, Congruent Ventures, SoftBank Group, SoftBank Vision Fund, Y Combinator, Capricorn Investment Group, Lightspeed Venture Partners, Mithril Capital Management and 2 more.
How much funding has Helion Energy raised?
Helion Energy has disclosed $477.1M raised across 3 of its 6 known rounds.
Where is Helion Energy headquartered?
Helion Energy is headquartered in Seattle, US.