Elite New York firms Sullivan & Cromwell, Wachtell Lipton Rosen & Katz and Davis Polk & Wardwell have picked up the lead roles on the US' latest multibillion-dollar buy-out.

An investment group headed by JC Flowers & Co has stumped up $25bn (£12.6bn) to acquire Sallie Mae, the largest student loan-provider in the US.

Wachtell is lead advisor to the investor group, which consists of JC Flowers, private equity firm Friedman Fleischer & Lowe, Bank of America and JPMorgan Chase. The Wachtell team is being led by co-chairman Edward Herlihy and includes corporate partners Craig Wasserman and Richard Kim, antitrust partner David Neill and tax partner Jared Rusman.

JC Flowers has also instructed Sullivan, which is fielding a heavyweight team from its New York office, headed by firm chair Rodgin Cohen, M&A partner Alan Sinsheimer and financial institutions partner Mitchell Eitel.

Davis Polk is advising the target.

The deal follows a string as hefty M&A deals in the first quarter as the market continues to flourish following a record year in 2006.

Earlier this month it was announced that Sullivan, Sidley Austin and Simpson Thacher & Bartlett had scooped the lead roles on the $29bn (£15bn) take-private of credit card processing group First Data.

Simpson Thacher is advising private equity giant Kohlberg Kravis Roberts & Co on the bid, while Sidley is acting for the target. Sullivan picked up a role acting on behalf of the company's independent directors.