Investor-owned utilities (IOUs) are private enterprises[1] acting as public utilities. Examples may range from a family that owns a well on their property to international energy conglomerates.[citation needed]
| Parent company | Operating company | Operating states |
|---|---|---|
| AES Corporation (AES) | AES Indiana, formerly Indianapolis Power & Light | IN |
| Dayton Power and Light | OH | |
| Allete (ALE) | Minnesota Power | MN |
| Superior Water, Light and Power | WI | |
| Alliant Energy (LNT) | Interstate Power and Light | IA |
| Wisconsin Power and Light | WI | |
| Ameren (AEE) | Ameren Illinois | IL |
| Ameren Missouri | MO | |
| American Electric Power (AEP) | AEP Ohio | OH, WV |
| AEP Texas | TX | |
| Appalachian Power | TN, VA, WV | |
| Indiana Michigan Power | IN, MI | |
| Kentucky Power | KY | |
| Public Service Company of Oklahoma | OK | |
| Southwestern Electric Power | TX | |
| American Transmission Company | American Transmission Company | WI, MI |
| Avista Corporation (AVA) | Avista Utilities | ID, WA |
| Black Hills Corporation (BKH) | Black Hills Energy | CO, SD, IA, KS, NE, WY |
| CenterPoint Energy (CNP) | CenterPoint Energy | TX |
| Fortis Inc. (FTS) | Central Hudson Gas & Electric | NY |
| Cleco Holdings | Cleco | LA |
| Consolidated Edison (ED) | Consolidated Edison | NY |
| Orange and Rockland Utilities | NY, NJ, PA | |
| CMS Energy (CMS) | Consumers Energy | MI |
| Dominion Energy | Dominion Virginia Power | VA |
| Dominion North Carolina Power | NC | |
| DQE | Duquesne Light | PA |
| DTE Energy Electric Company (DTE) | Detroit Edison | MI |
| Duke Energy (DUK) | Duke Energy Carolinas | NC, SC |
| Duke Energy Progress | NC, SC | |
| Duke Energy Indiana | IN | |
| Duke Energy Ohio | OH | |
| Duke Energy Kentucky | KY | |
| Duke Energy Florida | FL | |
| Edison International (EIX) | Southern California Edison | CA |
| Emera | Bangor Hydro Electric | ME |
| Maine Public Service | ME | |
| Énergir | Central Vermont Public Service | VT |
| Green Mountain Power | VT | |
| Entergy (ETR) | Entergy Arkansas | AR |
| Entergy Louisiana | LA | |
| Entergy Gulf States | LA | |
| Entergy Mississippi | MS | |
| Entergy New Orleans | LA | |
| Entergy Texas | TX | |
| Evergy (EVRG) | Evergy | MO, KS |
| Eversource Energy (ES) | Connecticut Light & Power | CT |
| Public Service New Hampshire | NH | |
| Western Massachusetts Electric | MA | |
| Exelon (EXC) | Commonwealth Edison | IL |
| Philadelphia Electric | PA | |
| Baltimore Gas & Electric | MD | |
| Potomac Electric Power | DC, MD | |
| Delmarva Power | DE, MD | |
| Atlantic City Electric | NJ | |
| FirstEnergy (FE) | Ohio Edison | OH |
| Cleveland Electric Illuminating | OH | |
| Toledo Edison | OH | |
| Pennsylvania Power | PA | |
| Penelec | PA | |
| Met-Ed | PA | |
| Jersey Central P&L | NJ | |
| Allegheny Energy | PA | |
| Monongahela Power | WV | |
| Potomac Edison | MD, WV, VA | |
| West Penn | PA | |
| Hawaiian Electric Industries (HE) | Hawaii Electric Company | HI |
| Hawaii Electric Light Company | HI | |
| Maui Electric Company | HI | |
| Iberdrola (IBE.MC) | Rochester Gas & Electric | NY |
| New York State Electric & Gas | NY | |
| Central Maine Power | ME | |
| Integrys Energy Group | Wisconsin Public Service Corporation | WI |
| Upper Peninsula Power Company | MI | |
| ITC Holdings | ITC Transmission | MI |
| Michigan Electric Transmission Company | MI | |
| ITC Midwest | IA, MN, IL, MO | |
| ITC Great Plains | OK, KS | |
| MDU Resources (MDU) | Montana-Dakota Utilities | MT, ND, SD, WY |
| MGE Energy (MGEE) | Madison Gas and Electric | WI |
| Berkshire Hathaway Energy | MidAmerican Energy Company | IA, IL, SD, NE |
| Pacificorp--Pacific Power | OR, CA, WA | |
| Pacificorp--Rocky Mountain Power | UT, WY, ID | |
| NV Energy | NV, CA | |
| National Grid plc (NGG) | New England Power | MA, NH, VT, CT, ME |
| Massachusetts Electric | MA | |
| Nantucket Electric | MA | |
| Granite State Electric | NH | |
| Niagara Mohawk Power | NY | |
| Long Island Lighting | NY | |
| NextEra Energy (NEE) | Florida Power & Light | FL |
| Gulf Power | FL | |
| NiSource (NI) | Northern Indiana Public Service Company | IN |
| NorthWestern Corporation (NWE) | NorthWestern Energy | SD, MT, NE |
| NRG Energy (NRG) | Reliant Energy | TX |
| NSTAR (NSARO) | Boston Edison | MA |
| Cambridge Electric Light | MA | |
| Commonwealth Electric | MA | |
| OGE Energy Corporation (OGE) | Oklahoma Gas & Electric | OK, AR |
| Otter Tail Corporation (OTTR) | Otter Tail Power | ND, MN, SD |
| PG&E Corporation (PCG) | Pacific Gas & Electric Company | CA |
| Pinnacle West Capital (PNW) | Arizona Public Service | AZ |
| PNM Resources (PNM) | Public Service Company of New Mexico | NM |
| Texas-New Mexico Power | TX | |
| Portland General Electric (POR) | Portland General Electric | OR |
| PPL Corporation (PPL) | PPL Electric Utilities | PA |
| Louisville Gas & Electric | KY | |
| Kentucky Utilities | KY | |
| Rhode Island Energy | RI | |
| Public Service Enterprise Group (PEG) | Public Service Electric & Gas | NJ |
| Puget Energy | Puget Sound Energy | WA |
| SCANA (SCG) | South Carolina Electric & Gas Company | SC |
| Sempra Energy (SRE) | San Diego Gas & Electric | CA |
| Southern Company (SO) | Alabama Power | AL |
| Georgia Power | GA | |
| Mississippi Power | MS | |
| TECO Energy | Tampa Electric | FL |
| UGI Corporation (UGI) | United Electric Company | PA |
| UIL Holdings Corporation | The United Illuminating Company | CT |
| UniSource Energy | Tucson Electric Power | AZ |
| UNS Electric | AZ | |
| Unitil (UTL) | Unitil Energy | MA, NH |
| Fitchburg Gas & Electric | MA | |
| Vectren (VVC) | Southern Indiana Gas and Electric | IN |
| Wisconsin Energy Corporation | We Energies | WI |
| Xcel Energy (XEL) | Northern States Power Company | MN, ND, SD, WI |
| Public Service Colorado | CO | |
| Southwestern Public Service | NM, TX |