Kingsley Napley is advising the UBS trader accused of costing the bank $2.3bn (£1.5bn) in losses through unauthorised trades, with Herbert Smith picking up a lead role advising the Swiss bank.

Criminal litigation partner Louise Hodges is advising Kweku Adoboli, who was last week (16 September) charged with one count of fraud by abuse of position and two counts of false accounting.

Adoboli is now being investigated by City of London Police in collaboration with the Financial Services Authority (FSA), the Serious Fraud Office (SFO) and the Crown Prosecution Service.

Kinglsey Napley is well-known for representing individuals facing regulatory or criminal investigation and also advised former derivatives broker Nicholas Leeson, who became infamous for bringing down Britain's Barings Bank in 1995 after accumulating $1bn (£637m) in unauthorised trading losses.

The firm is also advising former News International chief executive Rebekah Brooks in connection with the phone-hacking scandal at now defunct tabloid News of the World.

Other high-profile mandates include advising former London-based McDermott Will & Emery corporate partner Michael McFall when he was charged with insider trading by the FSA two years ago. Kingsley Napley criminal litigation partner Stephen Gentle won an acquittal for McFall on all charges in June 2010.

UBS, meanwhile, has turned to Herbert Smith, where London litigation partner Martyn Hopper is leading.

Herbert Smith was first appointed to UBS's global legal panel in 2009 as part of an eight-firm line-up.

Hopper, who was previously a senior in-house lawyer with the FSA, specialises in contentious regulatory work with a particular focus on financial institutions. His past experience includes representing former Shell chairman Sir Phillip Watts in an FSA investigation into Shell's reserves.

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