Many investors stand to win big when Anthropic goes public. Stakes held by firms including Menlo Ventures, Sequoia, Sound Ventures, and Spark Capital are expected to return billions.

Yet according to Anthropic’s S-1, none of those VC firms owns 5%, the threshold for being included in the principal stockholders’ table. That’s highly unusual. In a typical tech IPO, lead venture investors hold double-digit-percentage stakes in the startups they backed. The reason is Anthropic’s size. At its $965 billion private valuation, a 1% stake is worth nearly $10 billion, so, for example, Menlo’s roughly $14 billion position is only about 1.5% of the company, according to recently reported Bloomberg figures.

While the venture firms may lack sizable percentage stakes, Anthropic sold large stakes to strategic partners, companies that are also its business partners. Indeed, Amazon is likely the single largest financial beneficiary of the IPO.

Amazon first backed Anthropic in 2023 with a commitment to invest up to $4 billion in the AI company. Since then, Amazon has poured billions more into Anthropic. Instead of taking stock upfront, Amazon structured much of its investment as convertible notes, a type of debt that converts into shares upon an IPO or sale.

According to the S-1, Amazon holds convertible notes with $6.2 billion in principal outstanding as of June 30. That is Anthropic’s entire debt load. But as Anthropic’s valuation soared across successive funding rounds, the shares those notes will convert into became far more valuable. Amazon’s own filings valued its note holdings at $97.9 billion as of June 30.

As the value of Amazon’s convertible notes surged, Anthropic had to record the growing value of what it owes on its books. It reported the adjustments on its income statement under “change in fair value of convertible notes, derivative liabilities, and SAFEs,” a line that totaled $72.4 billion for the first half of 2026. The charge is non-cash, meaning no money left the company.

Amazon’s notes could convert into as many as 1.84 billion shares, according to the S-1. But a cap limits Amazon to 12% of Anthropic’s “partially diluted” share count, a figure that counts some shares not yet issued, such as stock options. Amazon can waive the cap. Notes that can’t convert will stay outstanding and convert in later quarters, subject to the same limit.

But the notes are only part of Amazon’s holdings. It further invested $10 billion in nonvoting preferred stock (a type of equity), in the second quarter, according to Amazon’s quarterly report for the period ended June 30. Amazon did this by investing $5 billion in each of Anthropic’s last two funding rounds. Combined with the $8 billion it invested in the notes from 2023 through 2025, that brings Amazon’s total investment to about $18 billion.

Beyond its stock gains, Amazon will also continue to earn significant revenue from Anthropic, which has committed to spend at least $110 billion on AWS over the next 10 years.

Google, too, is set for a major windfall from both the listing and its cloud computing deals with Anthropic. The search giant held about 14% of Anthropic as of early last year, according to court filings that were reported by The New York Times, and has invested more since, including $10 billion in April. (Google was likely diluted in subsequent and massive funding rounds, with PitchBook analyst Harrison Rolfes telling TechCrunch he estimates its current stake at closer to 5.6%.) It has also secured at least $114 billion in cloud commitments from the Anthropic through 2033.

While VCs set for massive paydays have little reason to complain, the S-1 makes it clear that the biggest winners of Anthropic’s IPO may well be tech giants like Amazon, which backed a would-be rival early on and now sell it much of the computing power it runs on.

The S-1 itself warns that some of those cloud providers also build rival AI models and that they may not always want the same things that Anthropic does.