Allen & Overy (A&O) has bagged a lead advisory role opposite Cravath Swaine & Moore on the sale of eye-care company Alcon to Swiss pharmaceuticals company Novartis – a deal that could be worth as much as $39bn (£20bn).

Cravath represented food giant Nestle on the sale of subsidiary Alcon, while A&O advised Novartis in a coup for the magic circle firm's US arm.

New York senior partner and US law co-head Dan Cunningham led the team for A&O, along with New York public M&A chief Eric Shube.

The Cravath team was led by the firm's managing partner, Robert Townsend, and fellow New York corporate partner Alan Stephenson.

Under the terms of the deal, which was announced today (7 April) and is subject to regulatory approval, Nestle will sell an initial 25% of its subsidiary to Novartis for $11bn (£5.55bn). Novartis will then acquire with the group's remaining 52% holding in Alcon before 2011 for a further consideration of $28bn (£14.1bn).

The role represents one of the most significant mandates to date for A&O's American practice and comes after Cunningham and Shube last year co-led the firm's team as international counsel on the $65bn (£32.8bn) restructuring of Tyco International. The City giant acted alongside main US counsel McDermott Will & Emery on that deal.

The sale continues a run of major deals between Nestle and Novartis, with Cravath last year bagging a lead role on the $5.5bn (£2.8bn) acquisition of Novartis' baby food brand by Nestle.

Alcon had sales of approximately $5.6bn (£2.83bn) in 2007. The company develops and manufactures pharmaceuticals, surgical equipment, contact lens solutions and other vision care products.

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