Funding timelineThe lab that started the modern AI boom, now the most heavily funded private company in history
OpenAI is the San Francisco research-and-deployment lab behind ChatGPT, GPT and Sora, founded in December 2015 as a nonprofit and restructured around a capped-profit subsidiary in 2019. Its funding arc defines the AI era: a US$1B Microsoft partnership in 2019, a US$10B Microsoft commitment at a ~US$29B valuation in January 2023, a US$6.6B round at US$157B in October 2024, a US$40B round at US$300B in March 2025 (then the largest private tech deal ever), and a record US$122B close at an US$852B post-money valuation in March 2026 — anchored by Amazon (up to US$50B), Nvidia (US$30B) and SoftBank (US$30B). OpenAI generates about US$2B in monthly revenue (2026), serves 900M+ weekly ChatGPT users, and is preparing a public listing. Cumulative funding is roughly US$142B on Frontier Rounds' conservative disclosed basis; third-party trackers that include credit facilities and rumored rounds put the figure at US$180–197B.
Every disclosed equity round for OpenAI, oldest to newest, with lead and participating investors where reported.
Initial ~US$130M actually received of a US$1B pledge from founders and backers; no formal priced round.
Microsoft's initial US$1B investment paired with an exclusive Azure compute partnership — widely credited with kicking off the contemporary AI boom.
Landmark multi-year US$10B Microsoft commitment, largely for Azure compute, at a reported ~US$29B valuation — double OpenAI's 2021 mark.
Employee tender priced around US$27–29B.
Thrive led with ~US$1.2B plus an option to add US$1B on hitting revenue targets.
Led by SoftBank, at the time the highest-value private technology deal in history.
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.
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.