Funded Biotechnology Startups in Waltham
Waltham, Massachusetts sits within Greater Boston's primary biotech corridor, and this set of 35 funded rounds—dated September 2020 through October 2025—re…
Waltham, Massachusetts sits within Greater Boston's primary biotech corridor, and this set of 35 funded rounds—dated September 2020 through October 2025—reflects a cluster weighted toward drug development, with roughly a dozen companies carrying "Therapeutics" or "Therapeutic" in their names. The largest disclosed raises are Thermo Fisher Scientific's $741M post-IPO debt round (October 2022), Kailera Therapeutics' $600M Series B (October 2025), and Zenas BioPharma's $200M Series C (May 2024). Series B is the most visible labeled stage, with six companies—including BostonGene ($150M, April 2022), Triveni Bio ($115M, October 2024), and Mythic Therapeutics ($103M, December 2021)—reaching that milestone. A meaningful share of rounds falls under "Series Unknown," meaning the specific tranche was not publicly disclosed. Activity was particularly dense in 2022 and has continued into 2025, with Kailera Therapeutics, Invivyd, Pretzel Therapeutics, and Xilio Therapeutics all raising within the first ten months of that year.
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Frequently asked
What are the largest disclosed rounds among Waltham biotech companies in this view?
Thermo Fisher Scientific leads with a $741M post-IPO debt round in October 2022, followed by Kailera Therapeutics' $600M Series B in October 2025 and Zenas BioPharma's $200M Series C in May 2024. BostonGene ($150M Series B, April 2022) and Ventus Therapeutics ($140M Series C, February 2022) are the next largest fully disclosed raises.
Which funding stage appears most often in this dataset?
"Series Unknown"—where the specific tranche was not publicly disclosed—is the most common tag across the 35 rows. Among explicitly labeled stages, Series B appears six times: Kailera Therapeutics, Triveni Bio, Spectrawave, BostonGene, Mythic Therapeutics, and Regenacy Pharmaceuticals.
How does 2022 compare to other years in terms of funding volume for Waltham biotech?
2022 had the highest single-year count in this view, with nine rounds closing across the year—from Ventus Therapeutics' $140M Series C in February to Thermo Fisher Scientific's $741M post-IPO debt in October. 2021 was close behind with eight rounds, including Mythic Therapeutics ($103M), Syndax Pharmaceuticals ($75M post-IPO equity), and Axial Therapeutics ($37M Series C).
Does any company appear more than once in this dataset?
Xilio Therapeutics raised twice within the rows shown: a $95M Series C in February 2021 and a separate $50M round in June 2025, making it the only company with multiple raises visible in this 35-row view.
Are any of these companies publicly traded?
Three companies show post-IPO rounds: Thermo Fisher Scientific ($741M post-IPO debt, October 2022), Syndax Pharmaceuticals ($75M post-IPO equity, December 2021), and EyeGate Pharmaceuticals ($11M post-IPO equity, August 2021), confirming they were already public at the time of those raises.
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