After a rollicking start in January and February, U.S. startup funding has slowed dramatically in March. American companies raised just around $13 billion in seed- through later- and growth-stage funding so far this month, per Crunchbase data. Unless momentum suddenly picks up, that puts March on track to deliver just a fraction of investment tallies from either of the prior two months, as charted below.   Slowdown more pronounced at late stage The slowdown is almost entirely due to fewer giant AI megarounds closing this month.  Given that, there’s a case to be made against reading too much into the topline numbers. After all, most of February’s huge tally came from a single round — OpenAI’s record-setting $110 billion fundraise — that happened to be announced on the second-to-last day of the month.  A couple weeks before that, Anthropic secured a $30 billion financing. Also in early February, robotaxi pioneer Waymo picked up $16 billion in fresh late-stage funding. Early- and seed-stage dealmaking in March, by comparison, is on track to come in close to the prior two months’ levels, as charted below.   Iran War and US investor jitters  The March startup funding slowdown also coincides with the Iran War, which commenced on Feb. 28. Broad stock indexes have fallen in tandem in subsequent weeks, although Monday did bring a much-awaited partial rebound. Notably, this month’s funding deceleration is mostly a U.S. phenomenon. European startup funding, by contrast, actually hit its highest point of the year in March, boosted by megarounds for AI infrastructure unicorn Nscale and artificial intelligence startup Advanced Machine Intelligence. February may be one for the record books While there are plenty of potential catalysts that could drive funding higher in coming weeks, both economic and geopolitical, it’s likely February’s U.S. funding tally will remain one for the record books.  Clearly, a $110 billion funding round — something without close precedent in startup history — will be  tough to top. If it does happen, it’ll likely take years, not weeks or months. For now, we’ll be keeping a close eye on the health of later-stage funding by more typical comps. By those measures, the March slowdown looks considerably less dire. Related Crunchbase queries: US Startup Funding, 2026 European Startup Funding, 2026 Related reading: Massive AI Deals Drive $189B Startup Funding Record In February While Public Software Stocks Reel  Global VC Investment Surged In January, With U.S. Dominating Funding, But A Pair Of AI Model IPOs In China  OpenAI’s New $110B Raise At A $840B Valuation Marks The Largest Venture Deal Ever Anthropic Raises $30B At $380B Valuation In Second-Largest Venture Funding Deal Of All Time Turing Winner LeCun’s New ‘World Model’ AI Lab Raises $1B In Europe’s Largest Seed Round Ever  Illustration: Dom Guzman