At a Glance
- U.S. AI startups raised $100 million+ each in 49 mega-rounds during 2025
- Eight companies secured multiple mega-rounds, up from three in 2024
- OpenAI led with a $40 billion March round at a $300 billion valuation
- Why it matters: Investors poured unprecedented capital into AI, signaling relentless sector growth
AI startups kept the capital spigot wide open throughout 2025, with 49 U.S. companies landing individual rounds of $100 million or more, according to News Of Philadelphia‘s tally. Eight firms closed two or more such mega-deals, nearly triple the prior-year count.
2025’s Top Funding Events
The year’s largest transactions were dominated by household names and rising infrastructure players:
| Company | Round | Month | Valuation |
|---|---|---|---|
| OpenAI | $40B Series C | March | $300B |
| Anthropic | $13B Series F | September | $183B |
| Thinking Machines Lab | $2B Seed | July | $12B |
| Reflection AI | $2B Series B | October | $8B |
| Anysphere | $2.3B | November | $29.3B |
| Cerebras | $1.1B Series G | September | $8.1B |
December Rush
The year ended with a flurry of outsized rounds:
- Unconventional AI scored a $475 million seed on December 8, valuing the one-year-old chip startup at $4.5 billion. Lightspeed and a16z co-led.
- Fal closed its third 2025 round on December 9, a $140 million Series D led by Sequoia that pushed valuation past $4.5 billion.
- Chai Discovery announced a $130 million Series B on December 15, co-led by Oak HC/FT and General Catalyst, pricing the biotech model builder at $1.2 billion.
- 7AI raised $130 million Series A on December 4, led by Index, for its cybersecurity agents.
- Mythic landed $125 million on December 17, led by DCVC, to scale power-efficient AI silicon.
Repeat Offenders
Eight companies raised multiple $100 million+ rounds in 2025:
- Anthropic – March and September
- Abridge – February and June
- Harvey – February and June
- Fal – July, September, December
- OpenEvidence – July, October
- Lila Sciences – March, October
- Hippocratic AI – January, November
- Anysphere – June, November
## Infrastructure Wave
Compute and platform startups captured massive checks as demand for training and inference soared:
- Lambda secured $480 million Series D in February, valuing the GPU cloud provider at $2.5 billion.
- Together AI raised $305 million Series B in February, reaching a $3.3 billion valuation for open-source model tooling.
- Baseten took in $150 million Series D in September, led by Bond, valuing the AI infrastructure firm at $2.1 billion.
- Groq closed $750 million Series D-3 in September, led by Disruptive, pushing valuation to $6.9 billion.
Sector Snapshots
Healthcare AI remained a magnet for capital:
- Hippocratic AI raised $126 million Series C in November at a $3.5 billion valuation.
- Abridge closed $300 million Series E in June, reaching $5.3 billion.
- Tennr landed $101 million Series C in June, valuing the automation startup at $605 million.
Legal tech also posted big numbers:
- Harvey hit $3 billion valuation with its February $300 million Series D.
- EvenUp raised $150 million Series E in October, valuing the personal-injury platform above $2 billion.
Early-Stage Giants
Several startups vaulted to unicorn status on seed or Series A capital:
- Unconventional AI – $475 million seed at $4.5 billion valuation
- Thinking Machines Lab – $2 billion seed at $12 billion valuation
- Periodic Labs – $300 million seed for AI scientist platform
2026 Preview
Momentum spilled into the new year as xAI unveiled a $20 billion Series E and Merge Labs closed a $250 million seed only weeks into 2026, setting the stage for another capital-heavy period.
Key Takeaways
- U.S. AI startups captured 49 nine-figure rounds in 2025, up from 43 in 2024
- OpenAI’s $40 billion round was the largest private AI deal on record
- Eight firms raised multiple mega-rounds, showing sustained investor appetite
- Infrastructure, healthcare, and legal tech dominated sector allocation
