Amazon Is Set to Be the Biggest Winner of Anthropic's IPO. By a Long Way.

Key points

• Amazon holds $6.2 billion in convertible notes (debt that turns into shares at IPO) in Anthropic, which Amazon's own filings valued at $97.9 billion as of June 30, 2026.
• Anthropic filed its S-1 registration statement with the SEC on October 26, 2026, the formal first step toward a public listing.
• Amazon's total cash invested in Anthropic reached roughly $18 billion across notes and preferred stock (shares with fixed terms but no voting rights).
• Anthropic has committed to spend at least $110 billion on Amazon's cloud platform, AWS, over the next ten years.
• No venture capital firm owns enough to appear in Anthropic's principal stockholders' table, which requires a 5% stake, an unusual situation explained by Anthropic's near-trillion-dollar private valuation.

When Anthropic filed its S-1 with the Securities and Exchange Commission on October 26, the headline grabbers were the venture firms: Menlo Ventures, Sequoia, Sound Ventures, Spark Capital. All are set for enormous paydays. None of them, though, will come close to Amazon.

The numbers inside the filing make that clear.

How did Amazon build such a large position?

Amazon structured most of its early investment as convertible notes, a form of debt that flips into company shares the moment a business goes public or gets acquired. It invested $8 billion in notes between 2023 and 2025. Then, in the second quarter of 2026, Amazon's own quarterly SEC filing shows it put a further $10 billion into nonvoting preferred stock by participating in Anthropic's last two funding rounds at $5 billion each. That brings the total cash outlay to roughly $18 billion.

As Anthropic's private valuation climbed toward $965 billion, those notes became extraordinarily valuable. Amazon's filings put the fair value of the notes alone at $97.9 billion as of June 30, 2026. The notes could convert into as many as 1.84 billion shares, though a cap keeps Amazon below 12% of Anthropic's share count, a cap Amazon can waive.

On Anthropic's own books, that swelling note value created a non-cash accounting charge of $72.4 billion for the first half of 2026. No money left Anthropic; the number simply reflects how much more valuable Amazon's future shares became. AI2Day has been tracking Anthropic's fast-rising revenues and costs, most recently its nine-times year-on-year customer spending growth and the power bill catching up alongside it.

Why don't the VC firms have bigger stakes?

They simply can't afford them at this scale. At a $965 billion private valuation, 1% of Anthropic is worth roughly $10 billion. Menlo Ventures reportedly holds around $14 billion worth of stock, impressive, but only about 1.5% of the company. No venture firm crossed the 5% threshold that would put it in the S-1's principal stockholders' table, which is genuinely unusual for a tech IPO.

Google is the only other investor in the same bracket as Amazon. Court filings reported by other outlets suggest Google held around 14% of Anthropic in early 2025, though subsequent funding rounds diluted that figure, with one analyst estimating a current stake closer to 5.6%. Google has also locked in at least $114 billion in cloud commitments from Anthropic through 2033.

Should Anthropic's future shareholders worry about this?

The S-1 itself flags the tension plainly: Amazon and Google both build competing AI models, and their interests won't always match Anthropic's. That's a real conflict worth watching. A company that relies on its biggest investors for the computing power it runs on, while those same investors compete with its products, is in a genuinely unusual position.

For now, Anthropic's growth gives it leverage. But the question of what AI agents do when nobody is watching is one this IPO filing won't answer.

The honest read of the S-1 is this: the VCs will do well; Amazon will do spectacularly. And it will keep earning from Anthropic's cloud bills long after the listing confetti settles.