HOUSTON, Jan. 2 (Xinhua) -- Avangrid, a U.S. subsidiary of global energy giant Iberdrola, announced on Tuesday it has ended a proposed multibillion-dollar merger of the Public Service Company of New Mexico (PNM), the largest electric utility in the U.S. state.

The deal, valued at more than 4.3 billion U.S. dollars excluding debt, was unanimously approved by PNM's board in 2020 in expectation to create a renewable energy operator with a combined market value topping 20 billion dollars. Iberdrola is a European leader in clean energy.

The New Mexico Public Regulation Commission rejected the merger in December 2021. PNM and Avangrid appealed the decision to the New Mexico Supreme Court in early 2022.

However, as the end date under the merger agreement passed on Dec. 31, 2023, the New Mexico Supreme Court still hasn't come to a decision in reviewing whether the merger should be allowed, according to a report from the Albuquerque Journal.

"While our merger agreement with PNM has been terminated, we remain more than ever steadfast in our commitment to New Mexico in the development of wind and solar renewables," an Avangrid spokesperson said in a news release.

PNM Resources Chairman and CEO Pat Vincent-Collawn said the company is greatly disappointed with Avangrid's decision.

"We had been looking forward to providing customers with the immediate benefits in our agreement and also the longer-term benefits of being part of a larger-scale entity with ties to global innovation and experience in the clean energy transition," she said in a statement.