Despite tighter markets in other sectors, AI startups in the US have continued attracting mega-rounds in 2025. By late August, 33 companies had raised $100 million or more, spanning healthcare, infrastructure, legal tech, media, and autonomous systems.
Last year saw 49 mega-rounds and seven $1B+ raises. This year’s pace suggests 2024’s momentum is carrying forward, with multiple billion-dollar rounds already closed and some startups raising more than one mega-round.
Standout deals in 2025
- OpenAI: Closed a $40B round in March at a $300B valuation, the largest raise in startup history.
- Anthropic: Raised $3.5B Series E at a $61.5B valuation.
- Thinking Machines Lab: Pulled in $2B seed funding, valuing the AI lab at $12B.
- Abridge: Raised two rounds in 2025, including a $300M Series E, bringing its valuation to $5.3B.
- Harvey: Legal AI startup secured two $300M rounds, now valued at $5B.
- Anysphere (Cursor): Scored $900M Series C, pushing valuation near $10B.
- EliseAI: Closed a $250M Series E at a $2.2B valuation in August.
- Runway: Raised $308M Series D at $3B valuation for its media production tools.
- Together AI: Pulled in $305M Series B at a $3.3B valuation.
- Celestial AI: Landed $250M Series C at $2.5B valuation.
Other big raises came from Shield AI ($240M), OpenEvidence ($210M), Lila Sciences ($200M seed), and ElevenLabs ($180M Series C).
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Where investors are betting
Healthcare and biotech remain a top draw, with startups like Ambience Healthcare ($243M), Tennr ($101M), and Insilico Medicine ($110M) securing large rounds. AI infrastructure players like Lambda ($480M), TensorWave ($100M), and EnCharge AI ($100M) also drew major backing, reflecting surging demand from AI model training and deployment.
VC heavyweights including Andreessen Horowitz, Kleiner Perkins, Sequoia, General Catalyst, Lightspeed, and Nvidia participated across many of these rounds.
With 4 months still left in 2025, analysts expect more $100M+ deals to close, solidifying this as another landmark year for AI funding.
