Amazon’s third-quarter 10-Q, filed on 30 October, puts its two Anthropic holdings on the balance sheet at about $238.7 billion at 30 September, by our arithmetic: nonvoting preferred stock recorded at “approximately $ 14.8 billion and $ 92.5 billion” at the end of 2025 and at 30 September, and convertible notes with an estimated fair value of “approximately $ 45.8 billion and $ 146.2 billion” at the same two dates.
The filing says Amazon put $8.0 billion into the notes from 2023 to 2025 and $10.0 billion into Anthropic nonvoting preferred stock in the first nine months of 2026. That is $18.0 billion of cash, so the stake is carried at about 13.3 times what Amazon paid, by our arithmetic.
Short explainer · Amazon Now Carries Its $18B Anthropic Bet at $238.7B
A vertical news Short narrated from this piece’s headline and opening line and related FourWeekMBA pieces.
Business Pill · VERTICAL INTEGRATION
A short explainer on vertical integration, when one company sits on several layers of the same value chain. It teaches the general idea only and says nothing about Amazon’s filing.
The key insight: Amazon’s 10-Q carries its two Anthropic holdings at about $238.7 billion against $18.0 billion of cash invested, about 13.3 times, by our arithmetic; most of the gain on the notes sits in accumulated other comprehensive income, not net income.
On the notes, the filing says the associated unrealized gain included in accumulated other comprehensive income “was $ 39.5 billion and $ 140.3 billion” at 31 December 2025 and 30 September 2026. On the preferred stock, it says Amazon recorded upward adjustments of “$ 7.2 billion and $ 62.8 billion for the nine months ended September 30, 2025 and 2026”, so $62.8 billion in the first nine months of this year.
The filing also records OpenAI. Amazon says it invested “$ 15.0 billion in Series C Preferred Stock of OpenAI” in the first quarter, “$ 13.7 billion of the Commitment Amount” in the second, and “the remaining $ 21.3 billion Commitment Amount” in the third, for a “$ 50.0 billion investment in Series C Preferred Stock”.
Across all its holdings, the 10-Q gives a total: “our recorded value in equity, equity warrant, and convertible debt investments in public and private companies was $298.8 billion”. Anthropic and OpenAI together are about $288.7 billion of that, by our arithmetic, or about 97%.
Amazon’s AI stakes as recorded in its Q3 2026 10-Q (Note 3): Anthropic convertible notes at an estimated fair value of $45.8 billion (31 Dec 2025) and $146.2 billion (30 Sep 2026); Anthropic nonvoting preferred stock at $14.8 billion and $92.5 billion; OpenAI Series C preferred stock at $50.0 billion, bought in 2026. Level 3 fair values, not sale prices. The $238.7 billion Anthropic total and 13.3x are our arithmetic.
Where the Gain Sits
The two Anthropic holdings are booked differently. The preferred stock is adjusted for observable price changes through “Other income (expense), net”, so those gains run through net income. The notes are “classified as available-for-sale”, so their gain goes to accumulated other comprehensive income on the balance sheet instead.
Meanwhile, the quarter’s income line moved the other way: the filing says other income (expense), net was “$10.2 billion and $(703) million during Q3 2025 and Q3 2026”, while the notes’ unrealized gain grew to $140.3 billion.
Amazon’s accumulated other comprehensive income rose from $28.2 billion to $102.3 billion over the nine months, and total stockholders’ equity from $411.1 billion to $613.6 billion, according to the balance sheet. The $298.8 billion of recorded investments equals about 49% of that equity, by our arithmetic.
The Business Lever: The Investor Is Also the Supplier
The same note ties the stakes to AWS. It says the 2026 Anthropic investment came with an amended commercial arrangement that “includes contractual obligations related to the performance of AWS chips”, and a financing facility “not to exceed $ 20.0 billion” that becomes drawable “as we reach certain delivery milestones of compute capacity”.
As we read Note 3, the two Anthropic instruments follow different accounting: preferred-stock gains reach net income through other income, while the notes’ $140.3 billion unrealized gain stays in equity.
As we read the note, Amazon is Anthropic’s investor and its supplier at once: the 2026 investment came with AWS chip obligations and a facility capped at $20.0 billion, of which $15.0 billion remains after a $5.0 billion Series H investment, tied to compute delivery milestones.
As we read the totals, Anthropic and OpenAI make up about 97% of the $298.8 billion of investments Amazon records, by our arithmetic, so the valuation of two private labs now moves a line worth about half of Amazon’s equity.
Amazon.com Inc., Form 10-Q for the quarter ended 30 September 2026
“Valuations of private companies are inherently more complex due to the lack of readily available market data.”
Three Implications
FOR AMAZON Its 10-Q records $298.8 billion of equity, warrant and convertible investments, against $613.6 billion of stockholders’ equity.
FOR ANTHROPIC Amazon’s facility is capped at $20.0 billion; the note says a $5.0 billion Series H investment reduced the amount available to $15.0 billion, which becomes drawable as AWS reaches compute-capacity delivery milestones.
FOR OPENAIAmazon completed its $50.0 billion Series C commitment with $21.3 billion in the third quarter, according to the 10-Q.
The framework says “the four largest U.S. cloud providers now hold roughly $2.1 trillion in revenue backlog, and half of that โ $1.05 trillion โ comes from two cash-burning AI startups”.
As we read it, Amazon’s 10-Q shows the other side of that concentration: the same two labs are now most of Amazon’s investment book. The framework predates this filing and does not discuss it.
What Is Not Established
These are Level 3 fair values, which the filing says rely on “discounts for lack of marketability” and other estimates; they are not sale prices. The notes are “subject to our 12 % ownership cap”. The 10-Q does not give a separate third-quarter figure for the Anthropic preferred-stock adjustment, and it says the investments are “Level 3 fair value measurements”.
This Week In The AI Supercycle
Execution Fault Lines, Concentrated Demand, and Geopolitical Firewalls
This week’s issue: the AI build is not short of demand for its parts. It is short of cheap money, and its end revenue rests on a narrow base of large, often venture-funded buyers.
Amazon’s 10-Q carries its Anthropic stake at about $238.7 billion against $18.0 billion invested and records a $50.0 billion OpenAI position inside $298.8 billion of investments. The $238.7 billion total, the 13.3x multiple and the 49% share of equity are our arithmetic from the filing.
A note on sourcing. Every figure comes from Amazon.com Inc.’s Form 10-Q for the quarter ended 30 September 2026, filed with the SEC on 30 October 2026. The values are Level 3 fair-value estimates as Amazon records them, not market prices. We did not contact Amazon, Anthropic or OpenAI. Figures labelled our arithmetic are our own.
Gennaro Cuofano is a CRO and tech executive who has worked in AI since late 2015, starting with bringing NLP, natural-language generation, voice and chatbot products to the marketing industry. His background is in law and finance: he holds a Master's degree in Law and an International MBA with an emphasis on corporate finance (LUISS Business School and the University of San Diego, 2012), and worked as a financial analyst at a real-estate investment firm in San Diego and as an assistant controller. His work focuses on business model strategy, business engineering and, more broadly, structural analysis: how companies make money, read from their own filings. He created FourWeekMBA and leads research there and at The Business Engineer, his newsletter on AI and business strategy, with over 95,000 subscribers and more than 1,000 published analyses. His writing has also appeared on Entrepreneur (for example, How to Digitize a Family Business in Europe) and HackerNoon. Find him on LinkedIn and Substack. See how we source.
