Funding timelineOpenAI is the lab behind ChatGPT, GPT and Sora, and the most heavily funded private company in history.
Every disclosed equity round for OpenAI, newest to oldest, with lead and participating investors where reported. Data is stored oldest-first; the timeline is displayed latest-first.
The largest private funding round in history, upsized from ~US$110B. Amazon committed up to US$50B (US$35B conditional on IPO/AGI milestones), Nvidia US$30B, SoftBank US$30B. First round to raise US$3B+ from individual investors via bank channels.
Led by SoftBank, at the time the highest-value private technology deal in history.
Thrive led with ~US$1.2B plus an option to add US$1B on hitting revenue targets.
Employee tender priced around US$27–29B.
Landmark multi-year US$10B Microsoft commitment, largely for Azure compute, at a reported ~US$29B valuation — double OpenAI's 2021 mark.
Microsoft's initial US$1B investment paired with an exclusive Azure compute partnership — widely credited with kicking off the contemporary AI boom.
Initial ~US$130M actually received of a US$1B pledge from founders and backers; no formal priced round.
OpenAI began in 2015 as a nonprofit pledged US$1B to develop AI 'for the benefit of humanity,' restructured around a capped-profit subsidiary in 2019 to fund compute, then reincorporated as a public-benefit corporation in October 2025 as it prepared for public markets. Each structural step unlocked a step-change in capital — the 2019 Microsoft deal, the 2023 US$10B, and the US$157B→US$300B→US$852B valuation ladder of 2024–2026.
ChatGPT turned OpenAI from a research lab into the fastest-growing consumer application in history. By March 2026 ChatGPT passed 900M weekly active users and 50M+ subscribers, with monthly revenue crossing US$2B; Microsoft integrates OpenAI models across Copilot and Windows, and OpenAI's enterprise base passed five million business users.
OpenAI's register is unique in spanning Microsoft (compute partner since 2019), SoftBank (co-lead of the 2025 and 2026 rounds) and Amazon (up to US$50B in 2026) simultaneously — the first time the three cloud giants share one frontier lab's cap table, with Nvidia as strategic investor and GPU supplier.
OpenAI's capital is spent on a ~US$600B cumulative compute program through 2030 (reported target), including Stargate data centres; the US$4.7B revolving credit facility closed alongside the 2026 round was undrawn at close. Frontier training runs now cost more than entire earlier funding generations.
With confidential filing expected in 2026, OpenAI's US$852B private valuation is the staging ground for what would be one of the largest public listings ever. Whether the round's conditional components (Amazon's US$35B tied to IPO/AGI milestones) convert depends on hitting both a public debut and AGI progress.
OpenAI's lead investors are profiled in the Investor Atlas when their firms join the directory. Track who backs every frontier AI round on the Funding Leaderboard.
Because it began as a nonprofit: of the founding US$1B pledge only about US$130M arrived as cash, and a charity cannot sell equity. Each structural step fixed that — the 2019 capped-profit recap unlocked Microsoft's US$1B, the October 2025 public-benefit reincorporation staged the public markets. Anthropic ran the sequence in reverse: born a C-corp in 2021, S-1 filed within five years.
Less than the headline: Amazon's commitment is up to US$50B, of which US$35B is conditional on IPO and AGI milestones, so the true size moves with OpenAI's own milestones. Nvidia and SoftBank at US$30B each anchor the firm portion, and the US$4.7B revolving credit facility was left undrawn at close — no comparable private round has relied this heavily on future events to complete its own total.
Because each anchors a different dependency: Microsoft is the compute partner dating to 2019; SoftBank co-led the two largest rounds (US$40B in 2025, US$122B in 2026) as the single biggest backer; Amazon arrived last with up to US$50B tied to milestones. Anthropic pairs two hyperscalers as suppliers; OpenAI needed three capital partners — a wider surface, but no single counterparty controls it.
That the funding gap is structural: US$2B monthly annualizes to about US$24B, while the reported compute program through 2030 totals roughly US$600B — some 25 years of current revenue. That arithmetic is why rounds are sized in tens of billions, why the revolver sat undrawn, and why Amazon's conditional US$35B keys to IPO and AGI events rather than revenue targets.
The first bought the relationship, the second scaled it: 2019's US$1B paired equity with exclusive Azure compute when OpenAI had no product; January 2023's US$10B — largely Azure compute — landed as ChatGPT's trajectory emerged and doubled the reported valuation to ~US$29B. SoftBank's US$40B in March 2025 then set a record OpenAI itself broke with the US$122B round a year later.