“Anthropic has started to eat a lot of OpenAI’s lunch, taking a lot of corporate customers away.”
Our reading, the sentence that was checked:
Anthropic is taking many corporate customers away from OpenAI.
Assessment: Unresolved Evidence as of
Where and when Gary Marcus wrote it
Marcus on AI, The rapid rise and slow decline of Sam Altman, paragraph 8.
- Said
- Source observed
- live page, full text, public
- Evidence as of
- the cutoff for this assessment
- Assessment recorded
- assessment marcus-the-rapid-rise-and-slow-decline-of-4454d9-a1
We recorded 18 claims from this post. See every claim from this post.
The wording above is the version this site observed on 2026-10-28. The source may have been edited after 2026-01-13. This page does not claim the wording was captured then.
What the claim commits to
- Kind
- Observation
- Deadline, as the speaker wrote it
- None stated. This site does not add one.
- Deadline state when assessed
- No horizon
- Deadline state on 2026-10-29
- No horizon (the release’s reference date)
From the speaker
- Anthropic
- taking a lot of corporate customers away
- OpenAI
- has started
Our interpretation
- The plain reading is that a substantial number of corporate customers moved purchases or workloads from OpenAI to Anthropic.
- A customer need not stop using OpenAI entirely, but adding Anthropic without displacing OpenAI does not establish the claim.
- Use calendar 2025, the latest completed annual enterprise-adoption period before the post, for this ongoing observation.
- Market-share changes are supporting context, not a direct count of customer transfers.
Counts as supported if: Customer-level purchasing records, a suitable survey, or multiple documented migrations establish substantial movement from OpenAI to Anthropic during the target period.
Counts as contradicted if: Comparable customer-level evidence shows little such movement and attributes Anthropic's gains predominantly to new demand or additions without meaningful displacement.
Retrospective: these criteria were written after the outcome was public.
Current assessment
Was it true for the period described?
Outcome: Unresolved
The record was checked, and the evidence available by the cutoff does not settle it.
Scored on a plain reading. The speaker named no measure for this claim, so it was judged on the reading an informed reader would take, stated below under our interpretation. Both reviews had to find that reading fair.
- Evidence as of
- Deadline state when assessed
- No horizon
- Assessment recorded
- Policy version
- 2026-10-28.7
Rationale
Anthropic's competitive gains are well documented. The stronger statement that it took many corporate customers from OpenAI is not established by market-share estimates. Menlo reports limited switching overall, while Ramp records growth for both firms. These findings leave customer transfers possible but unquantified.
Limitations
- Menlo has an investment in Anthropic.
- Menlo and Ramp measure different populations and forms of adoption.
- Growing customer totals do not rule out losses to a competitor.
Evidence (3 items)
Context only: Menlo Ventures via GlobeNewswire,
OpenAI ceded nearly half its share.
Why it matters here: Menlo reports Anthropic at 40% and OpenAI at 27% of the enterprise LLM API market. This supports competitive gains, but market share does not identify how many customers transferred; Menlo is an Anthropic investor.
- Publisher
- Menlo Ventures via GlobeNewswire
- Kind of source
- Company disclosure: the company describing itself, not an independent finding
- Describes events of
- Public from
Context only: Menlo Ventures,
Only 11% switched vendors.
Why it matters here: The survey of 150 technical decision-makers finds relatively limited vendor switching across providers. It does not identify the OpenAI-to-Anthropic portion, so it neither proves nor rules out substantial transfers.
- Publisher
- Menlo Ventures
- Kind of source
- Independent measurement
- Describes events of
- Public from
Context only: Ramp,
OpenAI grew both paid subscriptions
Why it matters here: Ramp reports December growth for both OpenAI and Anthropic. This cautions against treating Anthropic's growth as customer losses for OpenAI, although simultaneous growth can coexist with switching.
- Publisher
- Ramp
- Kind of source
- Independent measurement
- Describes events of
- Public from
What would settle it
A 2025 purchasing panel or customer survey measuring how many OpenAI customers shifted substantial spending or workloads to Anthropic.
Where it was said (1)
Said once in the sources this register covers.
: Marcus on AI, The rapid rise and slow decline of Sam Altman
Anthropic has started to eat a lot of OpenAI’s lunch, taking a lot of corporate customers away.
- Where
- paragraph 8
- Published
- 2026-01-13
- Source observed
- , live page
- Access
- full text, public
History
Assessment versions
- Assessment marcus-the-rapid-rise-and-slow-decline-of-4454d9-a1: Current. Outcome: Unresolved. Evidence as of 2026-10-28. Public date not recorded.
Recorded events
Assessment publishedBy this site
First assessment published after both reviews and the final-text check passed.
About assessment marcus-the-rapid-rise-and-slow-decline-of-4454d9-a1.