Simmons & Simmons and Macfarlanes have played key roles in an agreement that has seen NYSE Euronext take over the administration of Libor from the British Banker's Association (BBA). 

Simmons advised the Hogg Tendering Advisory Committee, which was charged with selecting a Libor administrator following much controversy over the bank interest rate during the past year.

The government-backed committee's recommendation for NYSE Euronext to oversee Libor will now take effect in early 2014. NYSE Euronext operates a number of stock exchanges including the New York Stock Exchange.

Simmons was appointed to advise the Hogg Committee in May this year, with corporate partner Charles Mayo and managing associate Rachel Lewis leading the firm's team.

The committee is led by Financial Reporting Council chair Baroness Hogg and includes a line-up of senior market and banking figures including the Bank of England's executive director of markets Paul Fisher and Legal & General Group chairman John Stewart.

BBA was advised on the agreement by Macfarlanes commercial partner Rupert Casey, while NYSE used its in-house legal team.

Last year Lawrence Graham was handed a lead role for the BBA on its independent probe into Libor. The firm fielded employment partner Helga Breen, white collar crime and fraud partner Eoin O'Shea and corporate partner Richard Everett.

Over the past year a host of law firms have landed roles for banks facing fraud allegations related to the ongoing rate-rigging scandal, including Clifford Chance, which has been advising both Barclays and the Royal Bank of Scotland, with a Chinese wall set up to avoid potential conflicts.

Meanwhile, earlier this year lawyers at Morrison & Foerster, Blackstone Chambers and Doughty Street Chambers advised on the high-profile application to ensure anonymity for 104 current and former Barclays employees named in a Libor test case.