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.