Allen & Overy (A&O) has advised pharma giant Novartis on its $28bn (£17.4bn) acquisition of a majority stake in Alcon, the world's largest eye-care company, reports The Am Law Daily.

The deal is the second stage of a larger transaction originally struck in spring 2008, when Novartis purchased a 25% stake in Alcon for $10.4bn (£6.5bn), handing the company an option to purchase the 52% of the company owned by Nestle.

A&O advised Novartis on that deal with a team led by Daniel Cunningham, who quit the firm last year to join US litigation leader Quinn Emanuel Urquhart Oliver & Hedges. However, the magic circle firm has maintained its relationship with Novartis, with M&A partner Eric Shube leading the firm's team on the new transaction. Novartis general counsel Thomas Werlen is a former A&O partner.

Wachtell Lipton Rosen & Katz also took a role for Novartis, with a team led by partners Andrew Brownstein and Trevor Norwitz.

Wachtell did not have a role on the original Novartis-Alcon deal, but the elite US firm does have a history with Novartis. The firm served as co-counsel alongside Shearman & Sterling on Novartis's purchase of two drug companies for more than $8bn (£5bn) in 2005.

Cravath Swaine & Moore advised Nestle – which until 2002 had owned the whole of Alcon – with partner Robert Townsend leading the firm's team.

Meanwhile, Sullivan & Cromwell is advising an independent committee of Alcon directors considering Novartis's offer to exchange $11.3bn (£7bn) of Novartis shares for the remaining 23% stake in Alcon currently held by minority shareholders. Nestle sold that chunk in an initial public offering in 2002.

Sullivan partner Keith Pagnani is leading the firm's team advising the Alcon board on the proposed share exchange.

This article first appeared on The Am Law Daily blog on americanlawyer.com.