Before joining Linklaters, Sum trained at the firm’s Australian alliance partner Allens. She joined Linklaters in 2002, moving to Barclays as a leveraged finance specialist in 2005 before returning to the Magic Circle firm in 2008 and making partner in 2010.
Sum is rated in The Legal 500 for her restructuring and insolvency work. Her experience includes leading on the £2.8bn restructuring of French clothing retailer Vivarte and acting on the £2.3bn restructuring of directories business Yell.
The Magic Circle partner will join Sidley a year after the firm also saw veteran restructuring partner David Ereira move to US firm Paul Hastings. Ereira was a rare lateral hire within the Magic Circle, having moved from Freshfields Bruckhaus Deringer to Linklaters in 2007.
Linklaters global banking group is led by Tony Bugg, the former head of restructuring and insolvency, a practice which is now led by global co-heads Rebecca Jarvis and Richard Bussell.
In February, Bugg had picked Sum to lead a push for greater market penetration in the shadow banking space. Sum had previously worked in Barclays Capital’s leveraged finance unit.
Sum will join former Linklaters veteran corporate partner Stephen Blackshaw at Sidley, who joined the US firm’s London office in 2012. Blackshaw is currently co-head of corporate at the London office, having spent 14 years at Linklaters, founding the firm’s Amsterdam office and leading its corporate group.
Linklaters relatively stable banking practice was previously led by now managing partner Gideon Moore. In private equity, the Magic Circle firm has seen more losses to US rivals, with five partners moving to Kirkland & Ellis in the past two years.
Sidley has sought to strengthen its base in the City with a six-partner hire earlier this year from Kirkland, allowing the US firm boost its London private equity offering.
Sidley co-chair of corporate restructuring and bankruptcy James Conlan said: ‘Yen has an excellent reputation in the market and is a welcome addition to our practice and to Sidley. She will also work with our growing team of private equity and finance lawyers as we expand the firm’s offering to clients in situations across the UK, the rest of Europe, Asia and the US.’
Linklaters said in a statement: ‘We can confirm that Yen Sum will be retiring from the firm at the end of the year. We thank her for contribution to the firm and wish her well.’
Read more on the City’s top banking teams in the feature: ‘Golden goodbyes – changing faces and fortunes at the City’s top banking teams’