Central Maine Power is owned by Avangrid, Inc., a Connecticut-based utility holding company that is itself wholly owned by Iberdrola, S.A., the Spanish energy multinational headquartered in Bilbao. So if you’re asking who owns CMP in Maine, the short answer is a Spanish parent company at the top, an American subsidiary in the middle, and the Maine utility at the bottom. Since December 2024, there are no public shareholders anywhere in that chain.
Avangrid, CMP’s Direct Parent
CMP is a wholly owned subsidiary of Avangrid, Inc., headquartered at 180 Marsh Hill Road in Orange, Connecticut.1Avangrid. AVANGRID Corporate Headquarters To Be in Orange Conn Avangrid groups CMP into its Networks business segment alongside six other electric and natural gas utilities, including New York State Electric & Gas, Rochester Gas and Electric, and United Illuminating in Connecticut. Together those utilities serve 3.3 million customers across New York and New England with a combined rate base of $11.7 billion.2Avangrid. Avangrid Networks
That shared structure matters in practical terms. CMP draws on administrative resources, technology platforms, and emergency crews from Avangrid’s other utilities. When a major storm hits Maine, repair crews can be dispatched from New York or Connecticut operations, and Maine crews travel the other direction when their sibling utilities need help.
Iberdrola, the Ultimate Owner
Avangrid is controlled by Iberdrola, S.A., a global energy company headquartered in the Torre Iberdrola in Bilbao, Spain.3Iberdrola. Corporate Headquarters Iberdrola supplies energy to close to 100 million people across Europe, North America, South America, and Australia, with main markets in Spain, the United Kingdom, Portugal, Brazil, Mexico, and the United States.4Avangrid. The Iberdrola Family of Companies
The U.S. market is a top priority for the Spanish parent. Iberdrola’s 2025–2028 strategic plan allocates roughly one-third of total global investment to the United States.5Iberdrola. Iberdrola in the United States CMP’s capital spending and grid upgrades are shaped by investment decisions made in Bilbao and filtered through Avangrid’s management in Connecticut.
What Changed in December 2024
Until the end of 2024, Avangrid traded on the New York Stock Exchange under the ticker AGR. Iberdrola already held 81.6 percent of the shares, and institutional and individual investors owned the remaining 18.4 percent. In May 2024, Iberdrola and Avangrid agreed on a buyout of the minority shares at $35.75 per share, a transaction valued at roughly $2.551 billion.6Iberdrola. Iberdrola and Avangrid Reach an Agreement to Acquire 100 Per Cent of the American Company
The merger closed on December 23, 2024, and Avangrid promptly asked the NYSE to suspend trading and delist its shares.7U.S. Securities and Exchange Commission. Avangrid Inc 8-K Filing Avangrid now operates as a wholly owned Iberdrola subsidiary, which means the entire ownership chain from a Maine customer’s meter to the top of the corporate pyramid runs through a single private company based in Spain.8Iberdrola. Iberdrola Completes Merger With Avangrid
What CMP Actually Does
CMP is Maine’s largest electricity transmission and distribution utility, serving about 670,500 customers across 346 communities in central and southern Maine.9Central Maine Power. Company Overview The company doesn’t generate electricity. It owns the poles, wires, and substations that deliver power to homes and businesses, and the delivery charge on your bill is CMP’s piece of the equation. Generation is a separate market that CMP is not part of.
Who Regulates a Foreign-Owned Utility
Private ownership doesn’t mean unchecked ownership. CMP answers to regulators at both the state and federal level, and no change of control can go forward without their approval.
The Maine Public Utilities Commission
The Maine Public Utilities Commission (MPUC) has direct authority over CMP’s rates, service quality, and corporate structure. Under Maine law, no public utility may transfer its stock or undergo a change in control without the commission’s authorization, and any transfer that violates the rule is void.10Maine State Legislature. Maine Revised Statutes Title 35-A 1103 – Transfer of Utility Stock The MPUC also sets delivery rates, reviews capital spending plans, and investigates customer complaints. After a spike in billing complaints, the commission launched an audit of CMP’s billing systems and customer service operations, and in late 2025 it rejected a proposed CMP rate increase, sending the company back to justify its requested spending.
The Federal Energy Regulatory Commission
At the federal level, the Federal Energy Regulatory Commission regulates interstate transmission and wholesale power markets.11Federal Energy Regulatory Commission. What FERC Does Under Section 203 of the Federal Power Act, any acquisition of utility securities or assets valued at more than $10 million requires FERC approval, with the commission evaluating effects on competition, rates, regulation, and the potential for cross-subsidization between utility and non-utility business lines.12Federal Energy Regulatory Commission. Mergers and Sections 201 and 203 Transactions Federal rules bar a utility with captive customers from selling to affiliates below market price or buying from them above market price, which in practice means Iberdrola and Avangrid cannot route CMP’s regulated revenue into unrelated ventures elsewhere.13eCFR. 18 CFR 35.44 – Protections Against Affiliate Cross-Subsidization
The Public Power Vote of 2023
CMP’s foreign ownership has been a live political issue in Maine. In November 2023, voters considered Question 3, the Pine Tree Power Company Initiative, which would have replaced both CMP and Versant Power with a consumer-owned nonprofit utility. Supporters argued public ownership would lower rates and improve accountability. Opponents, backed by heavy utility industry spending, warned of billions in acquisition costs and the risks of a government-run grid. Roughly 70 percent of voters rejected the measure.
The vote settled the immediate question, and CMP remains a privately owned utility whose profits flow to a parent company in Spain. The practical significance of that ownership chain for Maine ratepayers comes down to how well the MPUC and FERC guardrails work: whether regulators can compel adequate investment in grid reliability, keep delivery charges reasonable, and hold the company accountable when service falls short.