Businesses in Connecticut: the headquarters corridor, the insurers and all 89,234 workplaces

This page is for people who need to know which companies are in Connecticut and how to find the rest: job seekers, suppliers, analysts and B2B sellers planning a New England territory. It opens with the big headquarters, then covers the full business count by region and sector, and ends with how to look up a Connecticut business and how to prospect the state's insurers.

Top companies headquartered in Connecticut

The 15 largest SEC-listed companies whose latest 10-K gives a Connecticut principal executive office, by revenue in that filing. Employees are company-wide, in the filing's own terms.

All fiscal years ended in December 2025 except Stanley Black & Decker's, which ended January 3, 2026. Philip Morris's figure is net revenues, excluding excise taxes. Together the 15 reported $561.26 billion.

The next five are Gartner (Stamford, $6.50 billion), Silgan Holdings (Norwalk, $6.48 billion), SS&C Technologies (Windsor, $6.27 billion), Interactive Brokers (Greenwich, $6.21 billion of net revenues) and Hubbell (Shelton, $5.84 billion).

Many of these companies' people are mostly elsewhere. Booking Holdings reports about 2,900 of its 24,300 employees in the US; Amphenol, about 15,000 of 170,000. A Stamford or Norwalk headquarters often means a few hundred executives and corporate staff, which matters if you're selling something delivered to employees.

Who you might expect, and why they aren't listed

• Travelers reported $48.83 billion in 2025, but its 10-K names New York as the principal executive office and says it also maintains executive offices in Hartford.
• Eversource Energy ($13.55 billion) describes itself as headquartered in Boston and Hartford; its 10-K cover gives a Springfield, Massachusetts address.
• Synchrony Financial is based in Stamford but reports interest income rather than a revenue total, so it doesn't fit a revenue ranking.

Two clusters: Fairfield County and Greater Hartford

Fourteen of the 20 largest headquarters are in Stamford, Greenwich, Norwalk or Shelton, within commuting distance of New York. The other cluster is around Hartford, where Cigna, The Hartford, Stanley Black & Decker, Otis and SS&C sit within about 15 miles of the state capital, and where the insurance industry is concentrated.

Census data shows the insurance base directly. In 2023 Connecticut had 413 insurance carrier establishments employing 60,351 people, with average pay of $132,198 (our calculation from CBP payroll). Ninety-seven of those sites had 50 or more employees and 13 had 1,000 or more. The Census Bureau flags the carrier employment figure as moderately affected by the noise it adds for confidentiality. Aerospace is the other specialty: 84 aerospace product and parts establishments employ 31,549 people, also flagged for moderate noise.

How many businesses are in Connecticut

In bands: 75,307 establishments with 1 to 19 employees, 11,589 with 20 to 99 and 2,338 with 100 or more. CBP counts locations with paid employees across all sectors, not companies, and leaves out the self-employed; employment is for the pay period including March 12, 2023.

Businesses by planning region

Connecticut's eight counties stopped functioning as governments in 1960, and in 2022 the Census Bureau announced it would replace them with the state's nine planning regions in its statistics from late 2022. CBP 2023 reports by planning region:

Another 771 establishments with 31,725 employees are reported statewide without a region. The Capitol region has 30.8% of the state's jobs; Western Connecticut averages 14.6 employees per establishment against the Capitol region's 20.0: smaller workplaces, despite the big headquarters. For the capital itself, see businesses in Hartford.

What Connecticut businesses do

Manufacturing has only 3,735 establishments but averages 42.4 employees each, at $89,149 average pay. Educational services sites average 53.0 employees, a sign of large campuses. For the factory side, see manufacturing companies in Connecticut.

How to look up a Connecticut business

Prospecting Connecticut's insurers

Insurers keep their big central functions (claims, underwriting operations, IT, risk) in a few head offices with formal vendor onboarding. Work those, not every site.

Illustrative example. The company, prices and results are fictional, to show the method.

Nutmeg Tabletop (nutmegtabletop.example) runs cyber incident exercises for executive teams and wants Connecticut insurers.

• Insurance carrier establishments with 50 or more employees: 36 + 28 + 8 + 12 + 13 = 97.
• Some are second or third sites of the same carrier, so it estimates about 55 separate companies.
• It targets the chief information security officer and the head of operational resilience at each, not procurement.
• At six new clients a year at $30,000 per exercise, that's $180,000 of first-year revenue.

Separating a carrier's head office from its satellite claims office takes research on each site. Bebop can search for "insurance carriers in Greater Hartford with more than 200 employees and a CISO" and explain why each fits.

Subject: [Company]'s next incident exercise

Hi [first name],

Most carriers run their incident response exercise once a year, and the hard part is making it realistic for the executives, not the security team.

We run a half-day exercise built on a claims-system outage and a data extortion demand, with your general counsel, communications lead and CFO in the room, and we write the after-action report.

Could I send you the scenario we ran for a Hartford carrier your size?

[Your name], Nutmeg Tabletop

Next step: build the account list with how to build a prospect list.