Magic circle trio Freshfields Bruckhaus Deringer, Linklaters and Slaughter and May have snared the top roles on a joint venture agreement between pharmaceutical giants Novartis and GlaxoSmithKline (GSK).

The transformative deal will involve the two businesses combining their consumer healthcare units in a joint venture with revenues of £6.5bn. Novartis will also acquire GSK's oncology business for $16bn (£9.5bn) and sell its vaccines division, excluding the flu unit, to GSK for $7.1bn (£4.2bn). 

Freshfields and Linklaters provided joint corporate counsel for Novartis. For Freshfields, London managing partner Julian Long led along with London head of antitrust Rod Carlton and partners Thomas Janssens and Paul Yde. The Linklaters team was led by corporate partner James Inglis.

Hogan Lovells provided US corporate advice to Novartis, with a team led by New York M&A partner Adam Golden.

Slaughter and May corporate partner Simon Nicholls led the team advising GSK.

Cleary Gottlieb Steen & Hamilton is advising GSK on antitrust matters, with Washington partner George Cary leading. Niederer Kraft & Frey is advising on Swiss law matters, with corporate partner Philipp Haas leading.

GSK will have majority control of the JV with an equity interest of 63.5%.

Sir Andrew Witty, chief executive GSK said: "This proposed 3-part transaction accelerates our strategy to generate sustainable, broadly sourced sales growth and improve long-term earnings.Opportunities to build greater scale and combine high quality assets in vaccines and consumer healthcare are scarce. With this transaction we will substantially strengthen two of our core businesses and create significant new options to increase value for shareholders."

GSK shareholders are expected to receive a £4bn capital return from the deal.

Meanwhile, in a separate transaction Novartis has sold its animal health division to Eli Lilly for $5.4bn (£3.2bn) in an all-cash transaction. Freshfields again acted for Novartis on the deal, with Long leading.

Weil, Gotshal & Manges took the mandate for Lilly. The US firm fielded a multi-disciplinary team led by New York corporate partners Raymond Gietz and Matthew Gilroy

Both transactions are expected to close in the beginning half of 2015.

Joseph Jimenez, CEO of Novartis said: "The transactions mark a transformational moment for Novartis. We have also created a world-leading consumer healthcare business in our joint venture with GSK. We believe the divestment of our smaller Vaccines and Animal Health Divisions will enable us to realize immediate value from these businesses for our shareholders."

In 2012 Novartis finalised its first legal panel with magic circle trio Allen & Overy, Freshfields and Linklaters securing positions on its global roster.

In the same year, Slaughter and May collaborated with German and Italian best friends Hengeler Mueller and Bonelli Erede Pappalardo in advising GSK on its €470m (£393m) divestment of a portfolio of European over-the-counter (OTC) healthcare products to Omega Pharma.