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Phase Four develops radio-frequency plasma thrusters with flexible propellant options for smallsat and medium-class spacecraft propulsion.
DEFUNCTPhase Four developed radio-frequency electric propulsion for small satellites; in September 2025 it sold its Hall-effect thruster technology to Apex and its multi-mode propulsion technology and Hawthorne, California test facility to Quantum Space.
Phase Four developed radio-frequency electric propulsion for small satellites; in September 2025 it sold its Hall-effect thruster technology to Apex and its multi-mode propulsion technology and Hawthorne, California test facility to Quantum Space.
Provisional: the latest data refresh looked incomplete and was held, so these scores use inputs measured 2026-10-10.
Rank 131 of 156 ranked companies. With the pillars we have not measured for this company filled at the 10th and 90th percentiles of the companies we did measure, and every other company held at its published total, the rank is likely between 98 and 146.
3 of 6 inputs measured · Medium confidence · 81% of applicable weight backed by data
Not measured: Market value, Reported revenue
Not measured: Open-role change (90 days)
A pillar score averages the company’s percentiles among the tracked companies with a value: relative standing, not a grade. Inputs measured 2026-10-10 (UTC) · methodology v6. Every input, its value and percentile · How it is computed
The Space Score ranks companies relative to each other on public data we hold. It describes; it does not rate, forecast or recommend. It is not a credit rating and not investment advice. Full disclaimer
Sources: Founded, Status, Legal name
For information only, not investment advice. SpaceNexus is not a registered investment adviser, broker or dealer, and nothing here is a recommendation to buy, sell or hold any security. Data may be delayed, estimated or incomplete; check the source before acting. Full disclaimer
4 private rounds on record. Debt, grants, state capital, owner funding and acquisitions are listed under Funding history by class and not added in.
Radio-frequency plasma thruster offering propellant flexibility and high performance for LEO and beyond.
Checking for a discussion…
Compiled Oct 12, 2026 from 5 public records. Every figure links the record it comes from.
Form D notices
4 offerings reported on Form D
Latest filed Jan 17, 2025; first sale Jan 6, 2025; 1 of them last updated by an amendment (D/A)
Each offering counts once: a later amendment (Form D/A) replaces its original. Form D names no round label and no investors. Filings for a merger or SPAC deal are left out.
Latest sourced round
Series C (first close): $12.9M
Reported on Form D filed Jan 17, 2025; the date shown is the first sale
Source: SEC EDGAR
First sale Jan 6, 2025
Sourced rounds on record
4 rounds, $43.6M disclosed
Every round has a disclosed amount
Published rounds with a source link only, on the same rules as the funding tracker. Each round links the source that states its figure; amounts in other currencies are converted to dollars at the rate shown on the funding tracker.
APA
SpaceNexus. (2026, October 12). Phase Four: Company dossier [Data set]. Retrieved October 12, 2026, from https://spacenexus.us/company-profiles/phase-four
Chicago
SpaceNexus. "Phase Four: Company dossier." Data as of October 12, 2026. Accessed October 12, 2026. https://spacenexus.us/company-profiles/phase-four.
BibTeX
@misc{spacenexus_phasefour_2026,
author = {{SpaceNexus}},
title = {{Phase Four}: Company dossier},
year = {2026},
month = oct,
howpublished = {\url{https://spacenexus.us/company-profiles/phase-four}},
url = {https://spacenexus.us/company-profiles/phase-four},
urldate = {2026-10-12},
note = {Data as of 2026-10-12; each fact links its primary source}
}