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The documentS–1Anthropic, PBC26 OCT 2026 · 421 PP.
01The original SEC filingThe authoritative source, in your browser.SEC · HTML 02Download the saved filingThe complete 421-page document, optimized for downloading.PDF · 46 MB 03Download the full researchFindings, customer examples, calculations, and source references.Markdown

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Table of Contents

CSPs, sometimes referred to as hyperscalers, operate at global scale with significant infrastructure and market 
concentration. 

“customer” refers to a prosumer or an organization that uses our models, platform, or applications. 

“customers  with  $100,000  or  more  of  revenue  on  a  TTM  basis,”  “customers  with  $1  million  or 
more of revenue on a TTM basis,” and “customers with $10 million or more of revenue on a TTM 
basis”  each  refer  to  customers  contributing  revenue  equal  to  or  greater  than  the  applicable  dollar  amount 
during the trailing twelve-month (“TTM”) period ending on the measurement date. For purposes of this metric, 
we  define  a  customer  as  a  distinct  organization,  identified  by  aggregating  the  accounts  that  we  determine 
belong to the same organization based on internal records and available data. We do not separately define or 
internally  track  a  category  of  “enterprise”  customers,  and  our  customers  are  not  segmented  or  measured 
internally by reference to whether a given customer is an “enterprise.” Because spending $100,000 or more on 
our  products  is  generally  characteristic  of  organizational  rather  than  individual  usage,  we  use  the  number  of 
and revenue from customers with $100,000 or more of revenue on a TTM basis as our measure of enterprise 
adoption  and  engagement  with  Claude  throughout  this  prospectus,  including  in  references  to  “enterprise 
customers” and “enterprise adoption.”

“frontier AI” refers to AI systems at the current leading edge of capability and safety, performing at or near 
the highest levels of any existing system across a broad range of tasks.

“hallucinations” refer to outputs in which an AI model generates factually incorrect or fabricated information 
with apparent confidence.

“inference”  refers  to  the  process  by  which  a  trained  AI  model  processes  an  input  and  generates  an  output. 
Inference occurs each time a user or agent interacts with an AI system.

“interleaved  thinking”  refers  to  a  capability  whereby  an  AI  model  interposes  discrete  reasoning  steps 
between successive tool calls within a single response, rather than confining its reasoning to a single planning 
phase at the outset.

“interpretability” refers to research into how and why AI models produce specific outputs, with the goal of 
making model behavior more transparent and verifiable, especially in high-stakes applications.

“knowledge work” refers to complex cognitive work and related professional activities, including obtaining, 
producing,  analyzing,  and  communicating  information  through  tasks  such  as  coding,  drafting  analyses, 
synthesizing research, building financial models, and managing and automating documents and workflows. 

“LLMs”  refer  to  large  language  models,  or  AI  models  trained  primarily  on  large  datasets  to  understand  and 
generate natural language and computer code. 

“mechanistic  interpretability”  refers  to  a  subfield  of  interpretability  research  focused  on  reverse-
engineering  the  internal  computations  of  neural  networks.  Rather  than  inferring  model  behavior  from  inputs 
and outputs alone, mechanistic interpretability seeks to identify the specific features and circuits within a model 
that  give  rise  to  its  behavior  with  the  goal  of  making  model  reasoning  auditable  at  the  mechanism  level  and 
detecting failure modes, including deceptive or unsafe behavior, that may not surface in standard testing.

“model  weights”  refer  to  the  numerical  parameters  encoding  a  trained  AI  model’s  behavior,  which  are  the 
primary intellectual asset of a frontier AI developer, representing the accumulated investment in compute, data, 
and research.

“multi-agent orchestration”  refers  to  an  architecture  in  which  multiple  AI  agents  collaborate  on  a  shared 
task,  with  one  coordinating  while  others  execute  subtasks  in  parallel,  enabling  more  complex,  long-horizon 
work than a single agent can complete alone.

“Net  Revenue  Retention”  reflects  customer  expansion,  contraction,  and  churn  as  of  a  measurement  date. 
We calculate Net Revenue Retention by dividing the Qualified Customers’ Current Period revenue by their Base 
Period  revenue.  A  Qualified  Customer  is  a  customer  with  at  least  $1  of  revenue  during  the  Base  Period, 
excluding  subscribers  to  our  Claude  Pro  and  Max  plans,  whose  fixed-price  subscriptions  do  not  reflect  the 

2

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  1. Founders’ letterp. 3SEC
  2. Defined termsp. 12SEC
  3. Prospectus summaryp. 16SEC
  4. Risk factorsp. 38SEC
  5. Management’s discussion & analysisp. 144SEC
  6. Businessp. 190SEC
  7. Governancep. 254SEC
  8. Executive compensationp. 275SEC
  9. Related-person transactionsp. 293SEC
  10. Principal & selling stockholdersp. 299SEC
  11. Capital-stock rightsp. 303SEC
  12. Shares eligible for future salep. 318SEC
  13. Underwritingp. 327SEC
  14. Auditor change & expertsp. 345SEC
  15. Financial statements & notesp. 347SEC
  16. Part II & exhibit indexp. 413SEC

How this was made

Read in full.
Kept in context.

A snapshot of the filing dated , rather than a live record of later events.

3primary reviewers
421pages reviewed
43image instances checked

The review

Three primary reviewers read non-overlapping ranges of the complete main filing. All 43 embedded image instances were transcribed and visually reviewed, including the founders’ letter, charts, and customer case studies. Financial tables were also checked visually for dates, units, and column alignment.

A separate reviewer checked the draft’s calculations, accounting interpretations, and customer qualifications. An additional check covered the later merged findings. The result is 62 findings and 21 customer examples.

The boundary

Companion contracts and other exhibits named in the filing’s index are separate documents and were not independently reviewed. Customer outcomes, technical benchmarks, forecasts, and scientific priority claims remain attributed company or customer disclosures.

The numbers

Dollar figures are U.S. dollars. H1 means the six months ended June 30; Q2 means the three months ended June 30. The 2026 interim financial statements are unaudited. Our calculations show their inputs and are labeled separately from reported values.

Blank fields stay undisclosed. Figures with different periods, conditions, or potentially overlapping scopes are kept separate. An earlier tender price is not an IPO price.

What the evidence labels mean
Reported in filing
A company disclosure, with the period and accounting basis retained.
Company estimate / company claim
An estimate or assertion attributed to the company, with its uncertainty preserved.
Our calculation
A derived figure using cited inputs. It is not a separately reported company metric.
Customer example
A selected case study, with its measurement limits. It is not representative ROI.
Proposed / conditional
A status qualifier for an arrangement that is not yet effective or depends on stated conditions.

About updates. This edition is tied to the October 26, 2026 filing. Any later revision should identify its new source date and preserve the basis of earlier claims.

The footnotes are only the beginning.Explore the findings Read the story
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A closer look at the filing

Anthropic · Form S-1PDF 1

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Filed October 26, 2026. PDF is approximately 46 MB and opens only when requested. Section links may precede the exact cited paragraph.