Everyone keeps asking: “Are we in an AI bubble?” But just as often, I hear a different question, followed by recognition: “Wait—they raised another round?”
This year, a handful of top AI startups—some now so large that calling them “startups” feels vaguely ironic—have raised not just one giant round of funding, but two or more. And with each round, the startups’ valuations are doubling, sometimes even tripling, to reach astonishing new heights.
Take Anthropic. In March it raised a $3.5 billion Series E at a $61.5 billion valuation. Just six months later, in September, it pulled in a $13 billion Series F round. New valuation: $183 billion.
OpenAI, the startup that ignited the AI boom with ChatGPT, remains the pace setter, fetching an unprecedented $500 billion valuation in a tender offer last month. That’s up from the $300 billion valuation it garnered during a March funding round, and the $157 billion valuation it started off this year with as a result of an October 2024 funding.
In other words, in the 12 months between October 2024 and October 2025, OpenAI’s valuation increased by roughly $29 billion every month—almost $1 billion per day.
