| CONNECTICUT STEAM COMPANY THEBerlin, CT · Active | Berlin, CT | Corporation | May 21, 1965 | Active |
| HWP COMPANYLocation not reported, CT · Withdrawn | Location not reported, CT | Corporation | Feb 5, 1971 | Withdrawn |
| NORTHEAST NUCLEAR ENERGY COMPANYBerlin, CT · Active | Berlin, CT | Corporation | Nov 14, 1950 | Active |
| EVERSOURCE ENERGY SERVICE COMPANYHartford, CT · Active | Hartford, CT | Corporation | Sep 3, 1965 | Active |
| ROCKY RIVER REALTY COMPANY THEBerlin, CT · Active | Berlin, CT | Corporation | Apr 9, 1923 | Active |
| THE NUTMEG POWER COMPANYBerlin, CT · Active | Berlin, CT | Other | May 19, 1953 | Active |
| YANKEE GAS SERVICES COMPANYBerlin, CT · Active | Berlin, CT | Other | May 26, 1955 | Active |
| ELECTRIC POWER, INCORPORATEDLocation not reported, CT · Active | Location not reported, CT | Other | Jun 27, 1951 | Active |
| NORCONN PROPERTIES, INC.Berlin, CT · Merged | Berlin, CT | Corporation | May 10, 1988 | Merged |
| YANKEE ENERGY FINANCIAL SERVICES COMPANYBerlin, CT · Merged | Berlin, CT | Corporation | Sep 9, 1992 | Merged |
| CONNECTICUT LIGHT AND POWER COMPANY THELocation not reported, CT · Active | Location not reported, CT | Other | Jun 22, 1905 | Active |
| WESTERN MASSACHUSETTS ELECTRIC COMPANYLocation not reported, CT · Withdrawn | Location not reported, CT | Corporation | Jun 28, 1966 | Withdrawn |
| YANKEE ENERGY SERVICES COMPANYBerlin, CT · Merged | Berlin, CT | Corporation | Jul 2, 1993 | Merged |
| YANKEE ENERGY MARKETING COMPANYBerlin, CT · Dissolved | Berlin, CT | Corporation | Oct 13, 1995 | Dissolved |
| MODE 1 COMMUNICATIONS, INC.Berlin, CT · Merged | Berlin, CT | Corporation | Mar 26, 1996 | Merged |
| SELECT ENERGY, INC.Berlin, CT · Merged | Berlin, CT | Corporation | Sep 26, 1996 | Merged |
| CL&P RECEIVABLES CORPORATIONBerlin, CT · Dissolved | Berlin, CT | Corporation | Sep 5, 1997 | Dissolved |
| EVERSOURCE ENERGY FOUNDATION, INC.Hartford, CT · Active | Hartford, CT | Corporation | Sep 23, 1998 | Active |
| NORTHEAST GENERATION SERVICES COMPANYBerlin, CT · Active | Berlin, CT | Corporation | Dec 28, 1998 | Active |
| NU ENTERPRISES, INC.Berlin, CT · Active | Berlin, CT | Corporation | Dec 28, 1998 | Active |
| SELECT ENERGY CONTRACTING, INC.Berlin, CT · Merged | Berlin, CT | Corporation | Jul 21, 1999 | Merged |
| YANKEE ENERGY SYSTEM, INC.Berlin, CT · Active | Berlin, CT | Corporation | Feb 15, 2000 | Active |
| NGS SUB, INC.Berlin, CT · Active | Berlin, CT | Corporation | Jan 10, 2001 | Active |
| METROHARTFORD ALLIANCE, INC.Hartford, CT · Active | Hartford, CT | Corporation | Mar 29, 2001 | Active |
| EVERSOURCE ENERGY TRANSMISSION VENTURES, INC.Berlin, CT · Active | Berlin, CT | Corporation | Mar 19, 2010 | Active |
| EVERSOURCE ENERGY LAND TRUST, INC.Berlin, CT · Active | Berlin, CT | Corporation | Oct 15, 2012 | Active |
| EVERSOURCE WATER VENTURES, INC.Berlin, CT · Merged | Berlin, CT | Corporation | Oct 2, 2017 | Merged |