Read these primary sources
OpenAI itself filed no Form D, 10-K, 10-Q, 8-K, S-1, or DEF 14A under the "OpenAI" name through May 2026; the May 22, 2026 confidential draft S-1 is the first direct registration (not publicly readable while in draft form). The canonical primary-source set below is OpenAI's own news feed, Microsoft's blog (as Microsoft is the largest single counterparty across the 2019 / 2023 / 2025 / 2026 partnership events), the partner-side disclosures from Amazon and NVIDIA, and the Microsoft and Alphabet 10-Q footnotes that mark the OpenAI stake to fair value each quarter.
OpenAI's own news feed — funding rounds, recapitalization, partnerships
The canonical company-side source for every funding announcement, partner expansion, the October 2025 recapitalization, the April 2026 partnership revamp, and the Stargate program rollouts. The recurring refresh task walks every post on openai.com/news since the prior cycle.
# Funding rounds and corporate-event anchors
https://openai.com/index/accelerating-the-next-phase-ai/ # 2026-03-31 $122B round at $852B post-money
https://openai.com/index/introducing-openai/ # 2015-12-11 founding pledges
# Recapitalization and partnership terms
https://openai.com/index/next-chapter-of-microsoft-openai-partnership/ # 2025-10-28 recapitalization explainer
https://openai.com/index/next-phase-of-microsoft-partnership/ # 2026-04-27 partnership revamp
# Stargate
https://openai.com/index/five-new-stargate-sites/ # 2025-09-24 five new Stargate sites
https://openai.com/index/stargate-advances-with-partnership-with-oracle/# Oracle 4.5GW Stargate expansion
# Acquisitions
https://openai.com/index/openai-acquires-global-illumination/ # 2023-08 Global Illumination (first acquisition)
https://openai.com/index/openai-acquires-rockset/ # 2024-06 Rockset
# Enterprise milestone
https://openai.com/index/1-million-businesses-putting-ai-to-work/ # 2025-08 1M business customers
https://openai.com/index/frontier-alliance-partners/ # 2025 Frontier Alliances consulting program
Microsoft's blog and SEC filings — partner-side disclosures
Microsoft holds the largest single equity stake in OpenAI Group PBC and discloses fair-value carrying treatment in its 10-Q footnotes. Microsoft's blog is the canonical partner-side source for the 2019 / 2023 / 2025 / 2026 partnership-event anchors.
# Microsoft partnership-event anchors
https://blogs.microsoft.com/blog/2019/07/22/openai-forms-exclusive-computing-partnership-with-microsoft-to-build-new-azure-ai-supercomputing-technologies/ # 2019-07-22 initial $1B
https://blogs.microsoft.com/blog/2023/01/23/microsoftandopenaiextendpartnership/ # 2023-01-23 third multi-year
https://blogs.microsoft.com/blog/2025/10/28/the-next-chapter-of-the-microsoft-openai-partnership/ # 2025-10-28 recap-day post
https://blogs.microsoft.com/blog/2026/04/27/the-next-phase-of-the-microsoft-openai-partnership/ # 2026-04-27 revamp
# Microsoft EDGAR — search "OpenAI" in 10-Q footnotes for the fair-value mark
https://www.sec.gov/cgi-bin/browse-edgar?action=getcompany&CIK=0000789019 # Microsoft EDGAR filing index
CNBC, Bloomberg, Fortune, WSJ, Reuters, NYT — contemporaneous reporting
Reporter coverage for the recapitalization cap-table allocations (the ~$130B Foundation / ~$135B Microsoft / ~27% as-converted figures the joint announcement does not itemize), the unit economics around the May 22, 2026 S-1 (the negative ~122% non-GAAP operating margin reporting), and the underwriter cohort for the IPO process.
# March 2026 funding round
https://www.bloomberg.com/news/articles/2026-03-31/openai-valued-at-852-billion-after-completing-122-billion-round
https://www.cnbc.com/2026/03/31/openai-funding-round-ipo.html
# October 2025 recapitalization
https://www.cnbc.com/2025/10/28/open-ai-for-profit-microsoft.html
https://www.aljazeera.com/economy/2025/10/28/openai-restructures-into-public-benefit-firm-microsoft-takes-27-stake
https://fortune.com/2025/10/28/openai-restructure-for-profit-microsoft-pbc-long-term-gains-agi/
# April 2026 partnership revamp
https://www.cnbc.com/2026/04/27/openai-microsoft-partnership-revenue-cap.html
# May 2026 S-1 and unit economics
https://fortune.com/2026/05/22/openai-ipo-filing-1-trillion-may-finally-answer-these-big-questions/
https://fortune.com/2025/11/12/openai-cash-burn-rate-annual-losses-2028-profitable-2030-financial-documents/
Sibling Mungomash pages
The leadership-side mechanics of the founders, the November 2023 board episode, the for-profit conversion fight, and the senior-departures table live on the sibling leadership page. The Musk v. Altman docket lives on the lawsuits page. The ChatGPT product / version history lives on the cross-section versions page. The parallel-IPO-race sibling is Anthropic Financials.
# OpenAI on Mungomash
/orgs/openai/leadership/ # founders, board episode, departures table
/orgs/openai/lawsuits/ # Musk v. Altman + related litigation
/ai/chatgpt/versions/ # product / model version history
# Parallel-IPO sibling and partner-side financials
/orgs/anthropic/financials/ # Anthropic confidential S-1 filed Jun 2026
/orgs/microsoft/financials/ # Microsoft 10-Q OpenAI-stake footnote treatment
/orgs/oracle/financials/ # Oracle Stargate RPO treatment
/orgs/coreweave/financials/ # CoreWeave OpenAI customer-contract disclosures