Skadden Arps Slate Meagher & Flom and Ropes & Gray have taken the lead roles on a $9.5bn ($6bn) merger which will create one of the largest utilities companies in the US, reports The Am Law Daily.

Northeast Utilities has agreed to pay more than $4bn (£2.5bn) to absorb NSTAR, forming a company with a total enterprise value of $17.5bn (£11bn). The company will continue to be known as Northeast Utilities.

Northeast turned to Skadden for legal counsel on the merger, with M&A partners Michael Rogan and Sheldon Adler taking the lead, alongside partners from the firm's energy, tax, antitrust, M&A and executive compensation and benefits practices.

Meanwhile, NSTAR was advised by longstanding counsel Ropes & Gray.

Corporate partner David Fine led a Boston-based team that included tax partners Jonathan Zorn and Eric Elfman, environmental and real estate partner Peter Alpert, employment partner David Mandel and environmental and real estate partner Coke Cherney.

NSTAR's in-house lawyers included general counsel Douglas Horan and associate general counsel Richard Morrison.

Ropes & Gray has represented NSTAR – along with its predecessor, Boston Edison Company – for more than two decades.

Fried Frank Harris Shriver & Jacobsen advised Goldman Sachs, which served as chief legal advisor to NSTAR on the transaction.

The Am Law Daily is a blog on law.com, Legal Week's US affiliate title.