Alleghany Corporation website screenshot

Alleghany Corporation

Alleghany Corporation is a holding company engaged in property and casualty reinsurance and insurance through its subsidiaries, with additional investments in non-financial businesses held via Alleghany Capital. Founded in 1929 by railroad entrepreneurs Oris and Mantis Van Sweringen, the company transitioned over decades from rail holdings into specialty insurance and reinsurance, and is headquartered at One Rockefeller Plaza in New York City. Its principal insurance subsidiaries are Transatlantic Reinsurance Company (TransRe), a global reinsurer founded in 1977 with roughly 600 employees across 23 offices and more than $40 billion in claims paid to date; RSUI Group, a wholesale excess and surplus (E&S) underwriter spanning Property, Casualty, Professional Liability, Management Liability, and Binding Authority lines; and CapSpecialty, a specialty casualty and surety underwriter. Alleghany Capital holds non-insurance operating companies including toy and collectibles maker Jazwares (Squishmallows, Pokémon, Roblox, Fortnite licensed lines). On March 21, 2022, Berkshire Hathaway announced an $11.6 billion all-cash acquisition of Alleghany at $848.02 per share, which closed in October 2022. Alleghany now operates as a wholly-owned subsidiary of Berkshire Hathaway, contributing approximately $8.8 billion in 2025 gross premiums written and roughly $14 billion in insurance float to the parent. As a holding company whose operating units distribute exclusively through reinsurance intermediaries, wholesale brokers, and independent agents, Alleghany and its subsidiaries do not publish a developer portal, OpenAPI specifications, SDKs, or any other machine-readable API artifacts; the only digital surfaces exposed publicly are gated broker and agent login portals.

Alleghany Corporation is profiled on the APIs.io network. Tagged areas include Insurance, Reinsurance, Property and Casualty, Specialty Insurance, and Excess and Surplus.

3.0/100 minimal ▬ flat Agent 0/100 human only Full breakdown ↓
scored 2026-09-10 · rubric v0.20.0
0 APIs
InsuranceReinsuranceProperty and CasualtySpecialty InsuranceExcess and SurplusSuretyFinancial-ServicesHolding CompanyBerkshire Hathaway SubsidiaryToys And CollectiblesFortune 500

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-09-10 · rubric v0.20.0
Regulatory Posture applies to this provider. Its tags matched the Insurance regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.
Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.
The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from github.com/api-evangelist/alleghany: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Security Posture 1

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Alleghany Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Press 5

Recent news and press coverage referencing this provider.

Familiarity, similarity driving Berkshire's Alleghany deal

2026-05-25

Berkshire Hathaway to acquire Alleghany for $11.6bn

2026-05-25

Warren Buffett ends drought with Berkshire's $11.6 bln ...

2026-05-25

Berkshire Hathaway Insurance Vice Chair Calls AI 'Very ...

2026-05-25

Alleghany Capital Corporation Announces Investment In ...

2026-05-25

Resources

Get Started 1

Portal, sign-up, and the first successful call

Build 1

SDKs, sample code, and the tooling you integrate with

Access & Security 1

Authentication, authorization, and security posture

Operate 2

Status, limits, changes, and where to get help

Company 1

The organization behind the API

Other 5

Properties that don't map to a standard resource type

Source (apis.yml)

apis.yml Raw ↑
aid: alleghany
name: Alleghany Corporation
description: Alleghany Corporation is a holding company engaged in property and casualty reinsurance and insurance through
  its subsidiaries, with additional investments in non-financial businesses held via Alleghany Capital. Founded in 1929 by
  railroad entrepreneurs Oris and Mantis Van Sweringen, the company transitioned over decades from rail holdings into specialty
  insurance and reinsurance, and is headquartered at One Rockefeller Plaza in New York City. Its principal insurance subsidiaries
  are Transatlantic Reinsurance Company (TransRe), a global reinsurer founded in 1977 with roughly 600 employees across 23
  offices and more than $40 billion in claims paid to date; RSUI Group, a wholesale excess and surplus (E&S) underwriter spanning
  Property, Casualty, Professional Liability, Management Liability, and Binding Authority lines; and CapSpecialty, a specialty
  casualty and surety underwriter. Alleghany Capital holds non-insurance operating companies including toy and collectibles
  maker Jazwares (Squishmallows, Pokémon, Roblox, Fortnite licensed lines). On March 21, 2022, Berkshire Hathaway announced
  an $11.6 billion all-cash acquisition of Alleghany at $848.02 per share, which closed in October 2022. Alleghany now operates
  as a wholly-owned subsidiary of Berkshire Hathaway, contributing approximately $8.8 billion in 2025 gross premiums written
  and roughly $14 billion in insurance float to the parent. As a holding company whose operating units distribute exclusively
  through reinsurance intermediaries, wholesale brokers, and independent agents, Alleghany and its subsidiaries do not publish
  a developer portal, OpenAPI specifications, SDKs, or any other machine-readable API artifacts; the only digital surfaces
  exposed publicly are gated broker and agent login portals.
type: Index
deliveryModel:
  model: unknown
  open_source: false
  commercial: false
  callable_host: false
  label: Delivery model not determined — needs a product licence on record
  confidence: low
  source:
  - none
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source: []
  generated: '2026-07-22'
  method: derived
position: Consuming
access: 3rd-Party
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/alleghany.png
url: https://raw.githubusercontent.com/api-evangelist/alleghany/refs/heads/main/apis.yml
tags:
- Insurance
- Reinsurance
- Property and Casualty
- Specialty Insurance
- Excess and Surplus
- Surety
- Financial-Services
- Holding Company
- Berkshire Hathaway Subsidiary
- Toys And Collectibles
- Fortune 500
tags_raw:
- Insurance
- Reinsurance
- Property And Casualty
- Specialty Insurance
- Excess And Surplus
- Surety
- Financial Services
- Holding Company
- Berkshire Hathaway Subsidiary
- Toys And Collectibles
- Fortune 500
created: '2026-04-19'
modified: '2026-05-23'
specificationVersion: '0.23'
apis: []
common:
- type: DomainSecurity
  url: security/alleghany-domain-security.yml
- type: Website
  url: https://www.alleghany.com
- type: ContactUs
  url: https://www.alleghany.com/contact-us/
- type: ParentCompany
  url: https://www.berkshirehathaway.com
- type: Subsidiary
  name: TransRe (Transatlantic Reinsurance Company)
  url: https://www.transre.com
- type: Subsidiary
  name: RSUI Group
  url: https://www.rsui.com
- type: Subsidiary
  name: CapSpecialty
  url: https://www.capspecialty.com
- type: Subsidiary
  name: Jazwares
  url: https://www.jazwares.com
- type: AgentLogin
  name: RSUI Broker Portal
  url: https://www.rsui.com/brokers/
- type: PressRelease
  name: Berkshire Hathaway Acquires Alleghany (Mar 21, 2022)
  url: https://www.berkshirehathaway.com/news/MAR2122.pdf
- type: GitHubOrganization
  name: TransRe (empty - 0 public repos)
  url: https://github.com/TransRe
maintainers:
- FN: Kin Lane
  email: info@apievangelist.com

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