Company lists · Data refreshed September 2026

Top 25 Reinsurance underwriting companies based in the United States

Name: Reinsurance underwriting companies based in the United States
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 16, 2026 683 companies tracked

RevenueBase identified 683 reinsurance underwriting companies headquartered in the United States as of September 2026 and tracks 181,199 professional contacts across them, including 84,434 with verified work emails. New York is the largest hub.

This list covers reinsurance underwriting companies headquartered in the United States, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Every row shows the company's own description, its RevenueBase Smart Search rating, and when it was last checked. Data refreshed September 16, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase Smart Search, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.

How to read this list HQ checked on every row RevenueBase Smart Search rating on every row Refreshed Sep 16, 2026 86% judged on-target in blind review

683Companies

181,199Contacts tracked

84,434Verified emails

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The 25 largest reinsurance underwriting companies based in the United States

Ranked by team size

Top 25 of 683 reinsurance underwriting companies based in the United States, ranked by team size, largest first. Data refreshed Sep 16, 2026. RevenueBase Smart Search rates how each company's information relates to reinsurance underwriting companies: strong evidence (its own description names it), partial (names part of it), indirect (matched on the rest of its profile rather than the description shown). Click a contact count to view that company's people.
#	Company	RevenueBase Smart Search	Headquarters	Employees	Contacts
1	Liberty Mutual Insurance	Indirect evidence	Boston, MA, United StatesHQ checked Sep 16, 2026	10001+	30,330 contacts →
	Indirect evidence “At Liberty Mutual, we believe progress happens when people feel secure.” Source: RevenueBase Database · checked Sep 16, 2026
2	AIG	Indirect evidence	New York, NY, United StatesHQ checked Sep 16, 2026	10001+	23,438 contacts →
	Indirect evidence “American International Group, Inc.(NYSE: AIG) is a leading global insurance organization.” Source: RevenueBase Database · checked Sep 16, 2026
3	FM	Indirect evidence	Johnston, RI, United StatesHQ checked Sep 16, 2026	5,001-10,000	6,351 contacts →
	Indirect evidence “For nearly 200 years, FM has empowered businesses worldwide to manage risk, prevent loss, and build resilience.” Source: RevenueBase Database · checked Sep 16, 2026
4	Amwins	Indirect evidence	Charlotte, NC, United StatesHQ checked Sep 16, 2026	5,001-10,000	4,926 contacts →
	Indirect evidence “Amwins is the largest wholesale distributor of specialty insurance products and services in the U.S.” Source: RevenueBase Database · checked Sep 16, 2026
5	Reinsurance Group Of America, Incorporated	Partial evidence	Chesterfield, MO, United StatesHQ checked Sep 16, 2026	1,001-5,000	4,128 contacts →
	Partial evidence “Reinsurance Group of America, Incorporated (NYSE: RGA) is a global industry leader specializing in life and health reinsurance and financial solutions that help clients…” Source: RevenueBase Database · checked Sep 16, 2026
6	GUY Carpenter	Indirect evidence	New York, NY, United StatesHQ checked Sep 16, 2026	1,001-5,000	4,072 contacts →
	Indirect evidence “At Guy Carpenter, a Marsh business, we deliver a powerful combination of (re)insurance broking expertise, capital solutions, global analytics, advisory, and client support…” Source: RevenueBase Database · checked Sep 16, 2026
7	Sentry	Indirect evidence	Stevens Point, WI, United StatesHQ checked Sep 16, 2026	5,001-10,000	3,963 contacts →
	Indirect evidence “Sentry Insurance got its start in 1904, when members of the Wisconsin Retail Hardware Association formed their own insurance company.” Source: RevenueBase Database · checked Sep 16, 2026
8	Everest	Strong evidence	Warren, NJ, United StatesHQ checked Sep 16, 2026	1,001-5,000	3,411 contacts →
	Strong evidence “Everest Group, Ltd.(“Everest”) is a global underwriting leader providing best-in-class property, casualty, and specialty reinsurance and insurance solutions that address…” Source: RevenueBase Database · checked Sep 16, 2026
9	Markel	Indirect evidence	Glen Allen, VA, United StatesHQ checked Sep 16, 2026	1,001-5,000	3,151 contacts →
	Indirect evidence “As the insurance operations within the Markel Group Inc.(NYSE: MKL), we leverage a broad array of capabilities and expertise to create intelligent solutions for the most complex…” Source: RevenueBase Database · checked Sep 16, 2026
10	Mcgriff	Indirect evidence	Charlotte, NC, United StatesHQ checked Sep 16, 2026	1,001-5,000	3,021 contacts →
	Indirect evidence “When it comes to protecting what matters most in business and everyday life, at McGriff we believe our clients should never settle for less than the best.” Source: RevenueBase Database · checked Sep 16, 2026
11	RT Specialty	Indirect evidence	Chicago, IL, United StatesHQ checked Sep 16, 2026	1,001-5,000	2,955 contacts →
	Indirect evidence “RT Specialty is a leading wholesale distributor of specialty insurance products and services and the wholesale broking specialty for Ryan Specialty.” Source: RevenueBase Database · checked Sep 16, 2026
12	Crum & Forster	Indirect evidence	Morristown, NJ, United StatesHQ checked Sep 16, 2026	1,001-5,000	2,105 contacts →
	Indirect evidence “Crum & Forster (C&F) provides market leading property & casualty, accident & health, specialty and standard commercial lines insurance solutions.” Source: RevenueBase Database · checked Sep 16, 2026
13	Tokio Marine HCC	Indirect evidence	Houston, TX, United StatesHQ checked Sep 16, 2026	1,001-5,000	2,006 contacts →
	Indirect evidence “Tokio Marine HCC focuses on what matters most; our people.” Source: RevenueBase Database · checked Sep 16, 2026
14	QBE North America	Indirect evidence	New York, NY, United StatesHQ checked Sep 16, 2026	10001+	1,883 contacts →
	Indirect evidence “At QBE we’re driven by our purpose of enabling a more resilient future.” Source: RevenueBase Database · checked Sep 16, 2026
15	Berkshire Hathaway Specialty Insurance	Indirect evidence	Boston, MA, United StatesHQ checked Sep 16, 2026	1,001-5,000	1,799 contacts →
	Indirect evidence “Berkshire Hathaway Specialty Insurance is an organization committed to providing long-term risk solutions and claims care to our customers backed by the financial strength of…” Source: RevenueBase Database · checked Sep 16, 2026
16	GEN RE	Partial evidence	Stamford, CT, United StatesHQ checked Sep 16, 2026	1,001-5,000	1,542 contacts →
	Partial evidence “Gen Re is a leading property/casualty and life/health reinsurance company.” Source: RevenueBase Database · checked Sep 16, 2026
17	RLI Insurance Company	Indirect evidence	Peoria, IL, United StatesHQ checked Sep 16, 2026	1,001-5,000	1,386 contacts →
	Indirect evidence “RLI is a U.S-based specialty insurer that serves niche property, casualty and surety markets.” Source: RevenueBase Database · checked Sep 16, 2026
18	Radian	Indirect evidence	Wayne, PA, United StatesHQ checked Sep 16, 2026	1,001-5,000	1,262 contacts →
	Indirect evidence “Radian Group Inc.(NYSE: RDN) is a trusted, global multi-line specialty insurer, built to empower confident business decisions around the world.” Source: RevenueBase Database · checked Sep 16, 2026
19	ISO	Partial evidence	Jersey City, NJ, United StatesHQ checked Sep 16, 2026	5,001-10,000	1,097 contacts →
	Partial evidence “Underwriting solutions at Verisk is a leading provider of advanced tools and analytics for the property/casualty and life insurance industries.” Source: RevenueBase Database · checked Sep 16, 2026
20	Ryan Specialty	Partial evidence	Chicago, IL, United StatesHQ checked Sep 16, 2026	5,001-10,000	1,079 contacts →
	Partial evidence “Ryan Specialty (NYSE: RYAN) is an international specialty insurance firm that provides distribution, underwriting, product development, administration and risk management services…” Source: RevenueBase Database · checked Sep 16, 2026
21	Safety National	Partial evidence	St Louis, MO, United StatesHQ checked Sep 16, 2026	501-1,000	1,008 contacts →
	Partial evidence “Safety National is a leading specialty insurance and reinsurance provider.” Source: RevenueBase Database · checked Sep 16, 2026
22	HRH	Indirect evidence	Radnor, PA, United StatesHQ checked Sep 16, 2026	1,001-5,000	930 contacts →
	Indirect evidence “Willis Group Holdings plc is a leading global insurance broker.” Source: RevenueBase Database · checked Sep 16, 2026
23	Argo Group	Indirect evidence	New York, NY, United StatesHQ checked Sep 16, 2026	501-1,000	851 contacts →
	Indirect evidence “Argo Group is a U.S-focused underwriter of specialty insurance products in the property and casualty market.” Source: RevenueBase Database · checked Sep 16, 2026
24	Berkshire Hathaway Guard Insurance Companies	Indirect evidence	Wilkes-barre, PA, United StatesHQ checked Sep 16, 2026	1,001-5,000	843 contacts →
	Indirect evidence “Rated A+ Superior by AM Best (as of 8/13/25), Berkshire Hathaway GUARD Insurance Companies provides Property & Casualty insurance including Excess & Surplus lines.” Source: RevenueBase Database · checked Sep 16, 2026
25	Msig USA	Indirect evidence	New York, NY, United StatesHQ checked Sep 16, 2026	201-500	693 contacts →
	Indirect evidence “MSIG USA is the partner that businesses rely on for creative, customized insurance solutions.” Source: RevenueBase Database · checked Sep 16, 2026

RevenueBase Smart Search

RevenueBase Smart Search assesses information from a company’s LinkedIn profile, information supplied directly by the company, its website, and other publicly available sources. It uses that information to rate how closely the company relates to this list’s category: reinsurance underwriting companies. Every row carries its rating and the description the rating was read from, so each one can be checked rather than taken on trust.

Strong evidence: The company's own public description of its business names reinsurance underwriting companies.
Partial evidence: Its own public description names part of reinsurance underwriting companies, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name reinsurance underwriting companies. The match rests on the rest of the company's public profile rather than the one sentence quoted here, so this is the rating to check first.

RevenueBase Smart Search is how these lists are built: RevenueBase's data engine and AI assemble the companies that match a category defined in a user's own words, so a list can be about what companies actually do rather than about whichever industry code they were filed under.

Showing 25 of 683 reinsurance underwriting companies based in the United States

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Reinsurance underwriting companies based in the United States at a glance

As of Sep 16, 2026

46.6%Verified-email coverage

265.3Average contacts per company

11-50Median size (employees)

6.3%Largest-city concentration · New York

Sep 16, 2026Page data refreshed

Companies by employee count

1-10

232

11-50

233

51-200

201-500

501-1,000

1,001-5,000

5,001-10,000

10001+

Email recency for this list is measured worldwide rather than for United States, so it is reported there. Company counts and contact totals on this page are exact for United States, over 683 companies.

How this list was built

Company categories are rarely black and white. RevenueBase reads each company's own description of its business to decide whether it belongs among reinsurance underwriting companies, so some rows will be adjacent to the category rather than pure plays. The description and RevenueBase Smart Search rating on every row are there so you can check each match yourself.

Source: The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase Smart Search, the natural-language company search available to every RevenueBase user.
What qualifies: Companies headquartered in the United States whose own description of what they do matches “reinsurance underwriting companies”. Matching reads each company's description, not its industry code or its name.
RevenueBase Smart Search: RevenueBase Smart Search is how this list is assembled and how each row is rated. RevenueBase's data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to a category defined in a user's own words. Each row is rated strong evidence (its own description names reinsurance underwriting companies), partial evidence (it names part of the category) or indirect evidence (the description shown names none of it and the match rests on the rest of the company's profile). The description supporting each rating is quoted on the row.
What we exclude: Companies whose own description does not clearly place them among reinsurance underwriting companies, and records with no verified work email. Companies headquartered outside United States are excluded even when they keep an office there.
Match quality: In blind human judging of this matching method, 86% of matched companies were on target. Expect roughly 1 in 7 rows to be adjacent to the category rather than a pure play. Every row shows the company's own description and its RevenueBase Smart Search rating so you can judge each match yourself. Read the full methodology: how the lists are built, how the judging worked, and what the figure means.
Ranking: Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
Verification: Every listed company carries at least one verified work email, 84,434 across the full list. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
Refresh: This page's figures were pulled from the company graph on September 16, 2026. Lists refresh periodically as the graph is re-checked.
Corrections: Wrong category, wrong headquarters, or a company that has closed? Use “Report an issue” on any row. Reports go to the RevenueBase Data Team and feed back into the company graph.

Reinsurance underwriting companies by metro

Reinsurance underwriting companies in New York43
Reinsurance underwriting companies in Miami25

Frequently asked

What is RevenueBase Smart Search?

RevenueBase Smart Search is how RevenueBase decides which companies belong on this list and how strongly each one fits. Its data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to the category the list is about. Each row is rated strong evidence when the company's own description names reinsurance underwriting companies, partial evidence when it names part of the category, and indirect evidence when the description shown names none of it and the match rests on the rest of the company's profile.

How many reinsurance underwriting companies are there based in the United States?

RevenueBase identified 683 reinsurance underwriting companies headquartered in the United States as of September 2026, matched on each company's own description of what it does rather than its industry code.

What is the largest company on this list?

Liberty Mutual Insurance, headquartered in Boston, tops this list with the largest team on record.

Which city has the most reinsurance underwriting companies?

New York leads with 43 headquartered companies, followed by Miami (25) and Rolling Meadows (20).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work the top results, verified emails and direct dials included. Upgrading unlocks all 84,434 verified decision-maker contacts tracked across these 683 companies.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 16, 2026.

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About this data

RevenueBase is a B2B data infrastructure company. Its company graph covers 60 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph with RevenueBase Smart Search, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.