Anthropic files for a Nasdaq IPO, and its S-1 shows what a frontier lab costs to run

Anthropic, PBC filed a Form S-1 registration statement with the U.S. Securities and Exchange Commission on Monday, October 26, for a proposed initial public offering of its Class A common stock. The company said in a short announcement that it intends to list on the Nasdaq Global Select Market under the symbol ANT, with Goldman Sachs and Morgan Stanley named on the preliminary prospectus. The number of shares and the price range have not been set, and the registration is not yet effective, so nothing can be sold yet.

The filing matters less as a market event than as a document: it is the first time Anthropic has published audited financials, and it gives the most detailed public view yet of what it costs to run a frontier AI lab. Everything below comes from the S-1 itself unless stated otherwise.

Revenue grew fast; so did compute

Anthropic reports revenue of $41 million in 2023, $386 million in 2024 and $4.59 billion in 2025. For the first six months of 2026 it reports $16.29 billion, against $1.16 billion in the same period of 2025. The filing leaves blanks where third-quarter revenue and a run-rate figure as of October 31 will go; those numbers are not yet public.

The largest cost line is compute and infrastructure: $8.95 billion in the first half of 2026, about 55% of revenue in that period. In 2025 that line alone, $7.33 billion, was larger than total revenue. Personnel cost $3.15 billion in the half, and sales, marketing and partnerships $3.17 billion, up from $120 million a year earlier.

The result is an operating loss of $693 million for the first half of 2026, down from $2.14 billion in the first half of 2025 and from $8.06 billion for full-year 2025. That 2025 figure includes a $1.5 billion charge for the settlement of the Bartz copyright case.

An $80.7 billion net loss, mostly on paper

The headline net loss looks very different. Anthropic reports a net loss of $80.7 billion for the first half of 2026 and $42.0 billion for 2025. Most of that is non-cash: changes in the fair value of convertible notes, derivative liabilities and SAFEs added up to $72.4 billion in the half and $34.3 billion in 2025. The filing says these were driven mainly by its rising enterprise valuation, which increased the value of outstanding convertible notes. A further $8.76 billion of other expense appears in the half. In short, the operating business is close to break-even while the accounting for its funding instruments produces very large losses. The company still warns that it "may not achieve or sustain profitability in the future."

As of June 30, 2026, Anthropic held $131.7 billion in cash, cash equivalents and short-term investments.

Who pays

As of September 30, 2026, the filing counts more than 11,900 customers generating $100,000 or more in trailing-twelve-month revenue, up from more than 950 a year earlier. More than 1,900 spend $1 million or more, and about 250 spend $10 million or more. Anthropic reports net revenue retention of about 900%.

Concentration is a real risk. No single customer exceeded 10% of revenue in the nine months to September 30, but the top five together accounted for about 25%, and the filing notes that many large customers are not on long-term contracts and can cut spending at any time.

Control stays with the founders and the trust

The governance section is the most unusual part of the filing. Public investors will buy Class A shares with one vote each. A single Class F share, held by an LLC of the seven co-founders, will carry 50.1% of total voting power on general matters. A single Class T share, held by the Long-Term Benefit Trust, lets the trust elect the Class T directors, who will be a majority of the board. Class N shares, held mainly by strategic partners, carry no vote. Anthropic says it will qualify as a "controlled company" under Nasdaq rules.

Anthropic also contributed 846,840,960 Class N shares, 5% of its fully diluted shares as of June 30, to a wholly owned Anthropic Public Benefit Fund, and approved a framework to issue up to another 2% each time the share price rises 50% above the prior milestone. The co-founders have each pledged 80% of their equity to philanthropy. TechCrunch notes that this structure is controversial because voting power will not track economic ownership.

What it means for people who build on Claude

For developers, an S-1 does not change any API, price or model today. It does put on record a few things worth knowing. Anthropic runs on four chip families (AWS Trainium, Google TPUs, NVIDIA GPUs and AMD GPUs) and treats compute as one shared pool, which is its stated explanation for how it allocates capacity between research and customers. It also claims that Claude Opus 5.5 cut customer cost per task by about 40% compared with Claude Opus 5. That is the company's own measurement, without an independent check, but it shows the argument Anthropic will make to investors: falling cost per task leads to more usage.

The filing also confirms how much Anthropic depends on a small group of very large customers, and how heavily it is spending on compute commitments; the total committed amount is still blank in this draft. Both are reasons to watch for amended filings, which will fill in the offering size, price range and the missing third-quarter figures.

What is not in the filing

Reports citing people familiar with the plans have put a target valuation and a November listing date on the deal. Neither appears in the S-1, and Promptea has not been able to verify them. Until Anthropic files an amendment with a price range, the size and timing of the offering are unconfirmed.