FPL and Constellation Energy, rival US utilities, have abandoned their planned $11bn (€8.7bn) merger in the face of mounting regulatory resistance, just a month after state authorities forced Exelon and PSEG to walk away from a deal.

The deal between FPL and Constellation has been held up in the Maryland legislature for nearly a year as regulators have expressed reservations about how the deal would affect utility prices for customers. In June, the legislature decided to fire the state's Public Service Commission and appointed a new one to consider the merger.