A Central Maine Power Co. crew works to restore power on the Gray Road in Cumberland in December 2023. CMP’s parent company, Avangrid Inc., has been acquired by Spanish energy giant Iberdrola as part of a $2.5 billion deal that makes Maine’s biggest electric utility privately held. Bonnie Washuk/Portland Press Herald file

Spanish energy giant Iberdrola has completed its $2.5 billion acquisition of Central Maine Power’s parent company. The transaction makes Maine’s biggest electric utility privately held and reduces its visibility to federal securities regulators.

New York regulators approved Iberdrola’s purchase of the remaining 18.4% of Avangrid Inc. on Dec. 20 and the deal was completed Monday, with shareholders being paid $35.75 a share. The Federal Energy Regulatory Commission had signed off on the acquisition in September.

Iberdrola did not say when the deal will close. Shareholders will receive a proportional quarterly dividend until closing and will be paid on Jan. 2, it said.

The Maine Public Utilities Commission in September allowed the deal to move forward without state review. CMP rates were not an issue, but critics of the deal say it will undermine transparency in the utility’s operations.

Connecticut’s attorney general, state consumer counsel and others have urged the state’s utility regulators to review the acquisition. A proposed final decision by the Public Utilities Regulatory Authority (PURA) is expected on Jan. 27, but it’s unclear what it could accomplish now that the deal is completed. A spokeswoman for the agency did not respond Thursday to an email seeking information about the review following the deal’s completion.

In an email, Connecticut Attorney General William Tong criticized Iberdrola for completing the sale without giving Connecticut regulators the opportunity to act on the petition for review that he and Connecticut Consumer Counsel Claire E. Coleman filed. Iberdrola “should have provided the same deference to Connecticut’s regulator as it did in New York and Maine,” he said.

“We will continue arguing on behalf of ratepayers … because Iberdrola’s taking the company private removes its obligation to make public filings and removes a safeguard against risky corporate behavior that may impact public safety and household utility bills,” Tong said.

As a private company, Avangrid, which is headquartered in Connecticut, is exempt from filing financial and operational details with the U.S. Securities and Exchange Commission. The Maine Office of the Public Advocate and environmentalists said it would be a less transparent business and more difficult to monitor.

CMP said Maine regulators authorized Iberdrola’s indirect ownership of it and Maine Natural Gas in 2008 when Iberdrola acquired Energy East Corp., a predecessor of Avangrid. The PUC said the 2008 conditions included “extensive reporting requirements” and conditions to protect Maine utilities and ratepayers from financial harm.

In approving the deal, the New York Public Service Commission ordered Avangrid and its New York subsidiaries, New York State Electric and Gas and Rochester Gas & Electric, to file reports that would be required by the SEC showing financial results “as if Avangrid were still an SEC registrant.” State regulators said the order is “not a novel reporting requirement” because the two subsidiaries had previously operated under a similar requirement.

New York state also barred Avangrid’s subsidiaries from charging ratepayers for the costs of the transaction.

Iberdrola said the deal will allow it to “invest in the United States more efficiently.”

“The subsidiary will be able to participate more economically in new energy infrastructure projects in its grid and renewables businesses, representing a significant investment in local communities and the generation of hundreds of direct and indirect jobs,” it said.

The projects will create a “more robust, resilient and reliable electric grid” and help meet growing demand from utilities and data centers, Iberdrola said.

Tong and Coleman petitioned state regulators in September, asking them to review the Iberdrola-Avangrid deal. Avangrid is the parent company of three Connecticut utilities: the United Illuminating Co., Southern Connecticut Gas Co. and Connecticut Natural Gas Co.

“The PURA should carefully evaluate this proposed transaction to determine its impact on Connecticut utility customers, rates, operations, service and reliability,” Tong and Coleman said.

The transaction is “clearly a change of control,” requiring regulators’ review and approval, and Iberdrola and Avangrid have “made no attempt to show how customers might benefit in any way from this transaction,” they said.

Iberdrola and Avangrid argue that the transaction does not result in a new entity seeking to “exercise or attempt to exercise control” over a Connecticut public service company, which the companies say is a prerequisite to any review called for in state law. The transaction does “not implicate any currently effective regulatory obligations” of the companies, and Connecticut is not authorized to review the transaction, the companies said.