What is an S-1, and what did Anthropic file?
A Form S-1 is a registration statement filed with the SEC before a company first sells shares to the public. An initial public offering (IPO) is that first sale.
Anthropic, PBC filed its S-1 on EDGAR on Oct 26, 2026.[S1] Before that, EDGAR lists a draft registration statement (DRS) on Jun 1, 2026 and five amended drafts (DRS/A).[S2]
This guide walks through that one document, section by section. Page numbers are the ones printed in the prospectus.
What does the cover page tell you?
In the filing · Prospectus cover
Cover legend The information in this preliminary prospectus is not complete and may be changed.[S1]
A preliminary prospectus is a draft for the public. The shares "may not be sold" until the registration statement filed with the SEC is effective, the cover adds.
In the filing · Prospectus cover
Expected price range between $ and $[S1]
The blanks are real: no price range had been set. The number of shares, the underwriting discount and the proceeds are blank too.
In the filing · Prospectus cover
Proposed listing Nasdaq Global Select Market, symbol "ANT"[S1]
The company has applied to list its Class A common stock there. "Applied" means it had not yet listed.
The cover also says there are two kinds of sellers. Anthropic sells new shares, and "selling stockholders" sell existing ones. Anthropic receives no money from the second group.[S1]
The underwriters are the banks that buy the shares from the sellers and resell them. Goldman Sachs & Co. LLC and Morgan Stanley & Co. LLC are named as their representatives.[S1]
How is the prospectus laid out?
The table of contents on page i lists the sections in order.[S1] The main ones, with their first pages:
| Section | Page | What it answers |
|---|---|---|
| Prospectus Summary | 4 | The business and the offer in brief |
| Risk Factors | 26 | What the company says could go wrong |
| Use of Proceeds | 124 | What the company plans to do with the money |
| Capitalization | 126 | Cash and funding before and after the offering |
| Dilution | 129 | How book value per share changes for new buyers |
| Management's Discussion and Analysis | 132 | Management's explanation of the numbers |
| Principal and Selling Stockholders | 288 | Who owns the shares and votes |
| Description of Capital Stock | 292 | The share classes and their rights |
| Shares Eligible for Future Sale | 307 | When existing holders may sell |
| Consolidated Financial Statements | F-1 | The audited accounts |
What is in the prospectus summary?
The summary repeats the main facts in a few pages. "The Offering" box on page 18 lists shares offered, shares outstanding after the offering and the use of proceeds.[S1]
In the filing · Page 18, The Offering
Class F common stock to be outstanding after this offering 1 share[S1]
Most share counts in this box are blank. The special classes are not: Class T and Class F will each have one share, and Class E none.
The summary financial table on page 22 comes from the audited and interim statements later in the document.[S1]
In the filing · Page 22, Consolidated Statements of Operations Data
Revenue $4,585 (year ended Dec 31, 2025); $16,286 (six months ended Jun 30, 2026), in millions[S1]
Anthropic's fiscal year matches the calendar year. The six-month figures are from unaudited interim statements, as the page says.
In the filing · Page 22
Net loss $(41,965) (2025); $(80,748) (six months ended Jun 30, 2026), in millions[S1]
Brackets mean a negative number. A footnote says these totals include fair-value changes on convertible notes and similar instruments. They were $34.3 billion in 2025 and $72.4 billion in the 2026 half-year.
A convertible note is a loan that can turn into shares. The MD&A says the notes are recorded at fair value at the end of each period. So a rise in that value shows up as an expense.[S1]
How are the risk factors organised?
In the filing · Pages 27–119 (listed at page 26 in the table of contents)
Risk Factors Pages 27 to 119, in six groups[S1]
The groups: business and industry; privacy, cybersecurity and intellectual property; legal and regulatory; tax and accounting; governance; owning Class A stock.
Each risk factor opens with a one-sentence heading that states the risk. The paragraphs below it explain it, sometimes with past examples.
The section says the risks reflect the company's "beliefs and opinions" about what could affect it. One heading, on page 63, reads: "We have a history of net losses and may not generate sufficient revenue to achieve or sustain profitability in the future."[S1]
What does the use of proceeds section say?
In the filing · Page 124
Use of Proceeds general corporate purposes, including working capital, operating expenses, and capital expenditures[S1]
The S-1 names compute and infrastructure, hiring, and possible acquisitions. It also plans to pay tax withholding linked to settling some employee stock awards.
The dollar amounts are blank, and the section says the company will have "broad discretion" over the money.[S1]
What do the capitalization and dilution sections show?
The capitalization table has three columns: actual, pro forma and pro forma as adjusted. "Pro forma" means as if certain planned events, such as converting preferred stock into common stock, had already happened.[S1]
"Pro forma as adjusted" adds the offering itself. In the summary balance sheet on page 24, only the actual column is filled. The other two depend on the offering price.[S1]
Dilution compares the price new buyers pay with the net tangible book value per share after the offering. The S-1 defines net tangible book value as total tangible assets minus total liabilities and redeemable convertible preferred stock.[S1]
Where does management explain the numbers?
Management's Discussion and Analysis (MD&A) is listed at page 132; its text starts on page 133.[S1] It explains what drives revenue and costs, period by period, in management's words.
Anthropic's MD&A opens with its "financial model", built on four drivers it names. It also says it expects operating margin may compress as new compute comes online.[S1] That is a company statement, dated Oct 26, 2026.
In the filing · Page 24, Non-GAAP Financial Measures; reconciliation on page 156
Operating loss; Adjusted Operating Income (Loss) Operating loss $(693); the company's Adjusted Operating Income $1,618 (six months ended Jun 30, 2026, in millions)[S1]
Adjusted operating income is the company's own non-GAAP measure. It leaves out stock-based compensation ($2,185 million) and non-cash charitable contributions ($126 million). The S-1 defines it and reconciles it to GAAP in the MD&A.
Who owns the company before the offering?
The Principal and Selling Stockholders table is on page 289. It lists directors, top executives, holders of over 5% of a voting class, and selling stockholders.[S1]
In the filing · Page 289
All executive officers and directors as a group (7 persons) 496,360,810 Class A shares[S1]
The count is as of Sep 30, 2026. The percentage columns are blank in this S-1, as are the share totals they rest on.
"Beneficial ownership" follows SEC rules. It counts shares a person can vote or sell, plus options exercisable and RSUs expected to settle within 60 days.[S1] An RSU, or restricted stock unit, is a promise of shares once conditions are met.
How do the share classes work?
The Description of Capital Stock on page 292 has a table of each class's rights.[S1]
In the filing · Page 292, table of key terms
Votes per share Class A: 1; Class N: 0; Class T: 1; Class F: 50.1% of outstanding voting power on record date; Class E: 1[S1]
Class A is the class offered. Class N carries no vote except where the law requires one. Classes T, F and E have no economic rights, such as dividends.
In the filing · Page 289
Founder LLC, % of Total Voting Power After the Offering 50.1%[S1]
A footnote explains that while the Class F share exists, Class A holders' combined voting power is limited to 49.9%.
The Class T share is held by the Long-Term Benefit Trust (LTBT). It elects the Class T directors, who will be a majority of the board.[S1]
When can existing shareholders sell?
In the filing · Pages 307–308
Shares Eligible for Future Sale Release dates from the first trading day to the Q3 2027 earnings release or 365 days[S1]
The table lists dates when lock-up restrictions end for groups of holders. The share counts and percentages beside each date are blank.
The seven co-founders are locked up for up to 365 days after the prospectus date. It ends sooner if the Q3 2027 earnings release comes first.[S1] Some other holders have the same 365-day period. Non-founder directors and officers, some employees and some other holders have 180 days, or until the Q1 2027 earnings release if earlier. Staged earlier releases apply to several groups.
What do the financial statements add?
The F-pages hold the full statements and notes. The index on page F-1 lists the auditors' reports first, on page F-2.[S1]
In the filing · Page F-2
Report of Independent Registered Public Accounting Firm present fairly, in all material respects[S1]
This is the auditor's opinion on the 2025 statements. Its "critical audit matters" are areas the auditor found especially challenging to judge. Here they are loss contingencies and the convertible notes' fair-value estimate.
This guide skips some sections: Business, Our Governance Structure and Its Goals, Management, Executive Compensation and Underwriting. The same document gives each its own section.[S1]