Quinn Emanuel Urquhart & Sullivan London founding partner Marc Becker has left the firm, The Lawyer can reveal.

Becker is the fourth partner to exit in nearly as many months from the firm. Becker was one of the Quinn’s three original partners to launch the London office along with Richard East, who was hired from Kirkland & Ellis, and Sue Prevezer, who was formerly queens counsel at Essex Court Chambers.

According to Becker’s LinkedIn page he left the firm in June to establish his own freelance litigation and arbitration counsel, Marc Becker Law Limited, and continues to work with the firm, although it is not known in what capacity.

Quinn hired Becker from elite Los Angeles litigation firm Munger Tolles & Olson in 2008, when it was known as Quinn Emanuel Urquhart Oliver & Hedges. He specialised in entertainment, media and telecommunications industries in copyright, trademark and other commercial litigation.

He was transferred to London to bolster the US firm’s presence in the capital. LA-based senior partner Bill Urquhart said on hiring Becker that he was a “superstar”.

Since then, Quinn has become one of the most dominant litigation powerhouses in the City, toppling Jones Day as the world’s biggest litigation firm.

Quinn generated more revenue from litigation and arbitration last year than any other firm in the world at $1.204bn. Over the past five years Quinn Emanuel’s total disputes revenue has risen by 44 per cent from $835.5m.

Quinn has suffered a string of exits to US rivals during the year, including commercial litigator Martin Davies and financial regulatory lawyer David Berman to US rival Latham & Watkins in April and August respectively. Litigator Paul Friedman also joined Gunnercooke in June this year.

Quinn declined to comment.