· Venture Capital Tracker Editorial · investment-strategies
Impulse Space’s $308M Series D Extension: Combined Round $808M
Impulse Space added $308 million to its Series D on September 16, 2026, taking the combined round to $808 million. The company did not print a new mark. Reuters, citing a source close to the company, put the extension at $5.6 billion versus $4.26 billion on the June $500 million close.
Impulse Space added $308 million to its Series D on September 16, 2026, taking the combined round to $808 million. The company named returning checks from 137 Ventures, BANNER VC, DFJ Growth, Linse Capital, Lux Capital, and Valor Equity Partners. It did not print a valuation. Reuters, citing a source close to the company, put the extension at $5.6 billion — against $4.26 billion on the June $500 million close, also Reuters and a person familiar. Last verified September 17, 2026. Sources: company, Reuters Sep 16, Reuters June 2.
Three months after a $500 million D that already pushed lifetime capital past $1 billion, Impulse stacked another $308 million from the same book — and still refused to put a mark in the release.
Five-minute decision
| If you need… | Verdict |
|---|---|
| What happened | Extension closed. $308M added to Series D. Combined D = $808M. |
| New letter? | No. Not Series E. |
| Company valuation | Not disclosed. |
| Press mark | Reuters source $5.6B now vs $4.26B in June. Same reporter pattern. |
| Lifetime total | June post said $1B+ after the $500M. This release does not restate lifetime. Do not invent $1.3B. |
| Directory funds | Lux and Founders Fund (June D). |
Investigate further when: you underwrite post-launch mobility against named Space Force / SSC awards.
Wait or pass when: you treat $808M as incremental new capital, or $5.6B as a company print.
What the company did disclose
| Field | Detail |
|---|---|
| Company | Impulse Space — Redondo Beach. Founder/CEO Tom Mueller. Site: impulsespace.com. |
| Financing | $308M Series D extension · combined D $808M · Sep 16, 2026 |
| Investors (named, existing) | 137 Ventures, BANNER VC, DFJ Growth, Linse Capital, Lux, Valor Equity Partners, “among others” |
| Use | Product development, team, facilities. Headcount more than doubled over the past year (company; no absolute count here). |
| Vehicles | Mira (maneuvering), Helios (kick stage), Caravan (rideshare), Electra electric propulsion (unveiled; not a new close). |
| Government | Helios selected for U.S. Space Force NSSL Phase 3 Lane 1 — company says first upper-stage prime on that lane. $28M Space Systems Command Space Safari extension for VICTUS SALO 2 and 3. |
| Finance hire | First CFO: Adam Townsend, from VIZIO (IPO and Walmart sale). |
June D was co-led by 137 and BANNER; Founders Fund and Lux participated. This extension lists 137 and BANNER as participants, not as fresh leads. Do not rewrite June as superseded.
$500M vs $308M vs $808M
| June D | This extension | |
|---|---|---|
| Date | Jun 2–3, 2026 | Sep 16, 2026 |
| Amount | $500M | $308M added |
| Combined D | $500M | $808M |
| Company mark | Omitted | Omitted |
| Reuters mark | $4.26B (person familiar) | $5.6B (source close to the company) |
| Lead language | 137 + BANNER co-led | Existing investors participated |
If both Reuters figures are right, the mark moved about $1.3 billion in 15 weeks while the company added $308 million. That is a press-source path, not a cap table. The company still has not printed either number.
Space tape this month: Stoke ~$1B Series E (memo); The Exploration Company $450M C; Pixxel $100M C. Those are launch, capsule, and Earth-observation books. Impulse is after insertion.
What remains undisclosed
No company valuation. No lifetime restatement. No new-vs-existing dollar split. No backlog dollar figure. No ARR or revenue. Headcount is a rate, not a count. NSSL Lane 1 and the $28M SSC extension are awards the company named, not independently priced here.
June history: Impulse $500M Series D. Day index: September 16–17.
Follow Venture Capital Tracker in Google
Add VCT as a preferred source to make our venture-capital coverage easier to find in Google Search.
Last updated:
Editorial note: AI tools assisted with research, structure, or drafting. Venture Capital Tracker retains human editorial responsibility for factual accuracy, relevance, and source quality before publication.
