Weil Gotshal & Manges is to lose rated private equity partner Will Rosen. Rosen, who was the firm's first-ever corporate assistant in London when he joined 11 years ago, handed in his notice today (3 July).

He will officially leave the firm on Friday and is understood to be taking some time out over the summer before deciding on his next move.

The departure, revealed exclusively by legalweek.com, will be a blow to Weil Gotshal as Rosen – whose experience includes public M&A as well as private equity – was regarded as one of the office's rising stars and worked closely with London head Mike Francies.

He has acted for clients including private equity funds, corporates and investment banks. Past deals includes working alongside private equity partner Marco Compagnoni on the Barclay brothers' £100m acquisition of the De Vere Cavendish hotel in London's Jermyn Street and advising private equity houses Blackstone and Lion on the £1.27bn buyout of Cadbury Schweppes' European drinks business in late 2005.

Other clients have included General Electrical Commercial Aviation Services, Texas Pacific Group and Summit Partners.

His departure comes just over a year after Weil Gotshal brought in an eight-lawyer private equity team from Lovells, led by Compagnoni.

The loss of Rosen is the US law firm's first partner-level departure in London since corporate partner Graham Defries and securities partner Wayne Rapozo left to join Dechert in March last year.

Francies told Legal Week: "[Rosen is] a great guy; he's done a great job for us and he is also a good personal friend. But he has to do what he feels is best for him – it's a great shame."