# Spero Therapeutics funding: rounds and investors > Spero Therapeutics has raised $199M across 6 rounds since 2010. Investors include SR One, National Science Foundation and RA Capital Management. Source: https://millionrounds.com/company/spero-therapeutics (Millionrounds; every figure on the page links to its filing or article) United States · [Funded startup](https://millionrounds.com/companies) # Who invested in *Spero Therapeutics* 6 rounds we have observed, with the 21 investors named in them. Every figure came from a named source, and where the company reported a raise to the SEC itself, that is shown beside it. Biotech Healthcare Raised 4 months ago Funding summary Updated 26 Oct 2026 **$199M** raised across 6 rounds since 2010, from 7 sources **$3.0M** Series A **$30M** Series A **$52M** Series C **$9.0M** Round **$105M** Debt - **Latest round:** Debt, $105M Jul 2026 - **Step-up i:** 11.7× - **Investors:** 21 See who backed them ## The funding story Each circle is a round, placed by date and sized by amount. The line above is the running total. 2010 2013 2016 2019 2022 2025 **?** Seed **$3.0M** Series A **$30M** Series A **$52M** Series C **$9.0M** Round **$105M** Debt - **First round:** Seed - **Biggest round:** $105M - **Usual gap between rounds:** 3.8 years ## The rounds - **Jul 2026** Debt **$105M** *1 new* *3 returning* [National Science Foundation](https://millionrounds.com/fund/nsf-small-business-innovation-research-small-business-techno) [RA Capital Management](https://millionrounds.com/fund/ra-capital-management) [SR One](https://millionrounds.com/fund/sr-one) [HealthCare Royalty](https://millionrounds.com/fund/healthcare-royalty) Reported by HealthCare Royalty and 1 other - **Sept 2022** Round **$9.0M** *3 new* *1 returning* [National Science Foundation](https://millionrounds.com/fund/nsf-small-business-innovation-research-small-business-techno) [Google Ventures](https://millionrounds.com/fund/gv) [RA Capital Management](https://millionrounds.com/fund/ra-capital-management) [SR One](https://millionrounds.com/fund/sr-one) Source recorded SEC filing: $9.0M sold, first sale Nov 2022 - **Mar 2017** Series C **$52M** *8 new* *1 returning* [SR One](https://millionrounds.com/fund/sr-one) [Osage University Partners](https://millionrounds.com/fund/osage-university-partners) [Atlas](https://millionrounds.com/fund/atlas-2) [The Kraft Group](https://millionrounds.com/fund/the-kraft-group) [Lundbeckfonden Ventures](https://millionrounds.com/fund/lundbeckfonden-ventures) [MRL Fund](https://millionrounds.com/fund/mrl-fund) GV/ RA Capital Limited Rock Springs Reported by FinSMEs SEC filing: $43M sold, first sale Mar 2017 - **Jun 2015** Series A **$30M** *8 new* [Atlas Venture](https://millionrounds.com/fund/atlas-venture) [SR One](https://millionrounds.com/fund/sr-one) [Partners HealthCare Innovation](https://millionrounds.com/fund/partners-healthcare-innovation) [Lundbeckfond Ventures](https://millionrounds.com/fund/lundbeckfond-ventures) [GlaxoSmithKline](https://millionrounds.com/fund/glaxosmithkline) [Kraft Group](https://millionrounds.com/fund/kraft-group) [New England Patriots](https://millionrounds.com/fund/new-england-patriots) Merck Research Ventures From a historical funding record - **Apr 2014** Series A **$3.0M** *1 returning* [Atlas Partner](https://millionrounds.com/fund/atlas-partner) From a historical funding record - **Jan 2010** Seed **Amount undisclosed** *1 new* [Atlas Partner](https://millionrounds.com/fund/atlas-partner) From a historical funding record ## Founders and team From Spero Therapeutics's own website and the SEC filings it signed: 10 on the team. - **Esther Rajavelu** President and Chief Executive Officer - **John Raymond** Senior Vice President of Finance and Business Operations - **Sheila Finan** Senior Vice President Controller - **Timothy C. Keutzer** Chief Operating Officer - **Ankit Mahadevia** Executive Officer, Director i - **Cynthia C. Smith** Compensation Committee Chair - **Frank E. Thomas** Chairman of the Board; Audit Committee Chair - **Kamal C. Hamed** Executive Officer i - **Satyavrat Shukla** Executive Officer i - **Tamara C. Joseph** Executive Officer i On the board, as filed i *John C. Pottage* *Kathleen C. Tregoning* *Milind Deshpande* *Patrick E. Vink* *Scott C. Jackson* ## Who was in which round The busiest backers across the latest rounds. A filled square is a round they joined; a dark one, a round they led. **Seed** 2010 **Series A** 2014 **Series A** 2015 **Series C** 2017 **Round** 2022 **Debt** 2026 [SR One](https://millionrounds.com/fund/sr-one) [National Science Foundation](https://millionrounds.com/fund/nsf-small-business-innovation-research-small-business-techno) [RA Capital Management](https://millionrounds.com/fund/ra-capital-management) [Atlas Partner](https://millionrounds.com/fund/atlas-partner) [Google Ventures](https://millionrounds.com/fund/gv) [Atlas Venture](https://millionrounds.com/fund/atlas-venture) [Osage University Partners](https://millionrounds.com/fund/osage-university-partners) [Partners HealthCare Innovation](https://millionrounds.com/fund/partners-healthcare-innovation) [Lundbeckfond Ventures](https://millionrounds.com/fund/lundbeckfond-ventures) [GlaxoSmithKline](https://millionrounds.com/fund/glaxosmithkline) ## Everyone who backed them [SR One](https://millionrounds.com/fund/sr-one) Corporate VC **4** rounds [National Science Foundation](https://millionrounds.com/fund/nsf-small-business-innovation-research-small-business-techno) Government **2** rounds [RA Capital Management](https://millionrounds.com/fund/ra-capital-management) Private equity **2** rounds [Atlas Partner](https://millionrounds.com/fund/atlas-partner) VC firm **2** rounds [Google Ventures](https://millionrounds.com/fund/gv) Corporate VC **1** round [Atlas Venture](https://millionrounds.com/fund/atlas-venture) VC firm **1** round [Osage University Partners](https://millionrounds.com/fund/osage-university-partners) VC firm **1** round [Partners HealthCare Innovation](https://millionrounds.com/fund/partners-healthcare-innovation) Corporate VC **1** round [Lundbeckfond Ventures](https://millionrounds.com/fund/lundbeckfond-ventures) VC firm **1** round [GlaxoSmithKline](https://millionrounds.com/fund/glaxosmithkline) VC firm **1** round [Atlas](https://millionrounds.com/fund/atlas-2) Private equity **1** round [The Kraft Group](https://millionrounds.com/fund/the-kraft-group) Investment firm **1** round [Kraft Group](https://millionrounds.com/fund/kraft-group) Investment firm **1** round [Lundbeckfonden Ventures](https://millionrounds.com/fund/lundbeckfonden-ventures) VC firm **1** round [MRL Fund](https://millionrounds.com/fund/mrl-fund) Company **1** round [HealthCare Royalty](https://millionrounds.com/fund/healthcare-royalty) Investment firm **1** round [New England Patriots](https://millionrounds.com/fund/new-england-patriots) VC firm **1** round GV/ RA Capital no record of our own yet **1** round Limited no record of our own yet **1** round Merck Research Ventures no record of our own yet **1** round Rock Springs no record of our own yet **1** round Missing a round, or an investor who was in one? [Tell us](https://millionrounds.com/corrections?slug=spero-therapeutics). ## Quick answers about Spero Therapeutics ### Who invested in Spero Therapeutics? Spero Therapeutics's investors include SR One, National Science Foundation, RA Capital Management, Atlas Partner and Google Ventures, and 16 more on record. ### How much has Spero Therapeutics raised? Spero Therapeutics has raised $199M across 6 rounds since 2010. One round did not disclose an amount, so the total is a floor. ### When did Spero Therapeutics last raise? Spero Therapeutics's most recent round was a Debt of $105M in Jul 2026. ### What was Spero Therapeutics's biggest round? Its most recent round, $105M in Jul 2026, is also its largest on record. ### Who backed Spero Therapeutics first? Spero Therapeutics's first round on record, in Jan 2010, was backed by Atlas Partner. ### What stage is Spero Therapeutics at? Spero Therapeutics's latest named round is a Debt, in Jul 2026. ### Where is Spero Therapeutics based? Spero Therapeutics is based in the United States. ## Companies like Spero Therapeutics In the same sector, and raised in the last eighteen months. [**Star Therapeutics** $325M · Oct 2026](https://millionrounds.com/company/star-therapeutics)[**Promaxo** $106M · Oct 2026](https://millionrounds.com/company/promaxo)[**Prolific Machines** $105M · Oct 2026](https://millionrounds.com/company/prolific-machines)[**AI** $18M · Oct 2026](https://millionrounds.com/company/ai)[**IMIO** $19M · Oct 2026](https://millionrounds.com/company/imio)[**Baba** $40M · Oct 2026](https://millionrounds.com/company/baba) ## Find investors like these Search every investor by what they have actually funded, then narrow to your stage and market. Free. Open the investor searchOr these rounds in the app