UBS has suffered a mass defection of staff from its wealth management business in Mayfair, London, with more than 50 people leaving for rival companies in the space of a fortnight.

The poaching has been led by Vestra Wealth, a start-up financed in part by Goldman Sachs and headed by David Scott, who until last May headed UBS wealth management for UK customers. Vestra has taken 52 staff and other senior people have moved to Merrill Lynch, Rothschild and Credit Suisse in the past few days.

The defections leave the ranks of the business serving UK-domiciled clients significantly thinned, with two thirds of its 80 front office and support staff leaving. That division has £4.6 billion under management. A typical client would have about £1million in liquid assets. The defection leaves an estimated £3billion-worth of business at risk of being poached but senior staff are limited by non-solicit covenants, which prevent them from directly approaching former clients for up to six months. Some have to take gardening leave as well.

It is not the first staff defection at the business, formerly the investment management division of Laing & Cruickshank. In 2006, many staff left to join Cheviot Asset Management.

John Pottage, chief executive of UBS wealth management in the UK, played down the departures, saying only 20 client advisers had left. “We have taken all necessary steps to ensure our clients continue to receive the level of professional service they would normally expect.

“It is entirely normal to see a peak in client adviser departures at this time of year following the bonus season.”

UBS has more than 300 investment advisers in London but its reputation has been hit by vast sub-prime losses in America and by allegations of tax evasion by a UBS client that have led the bank to advise some senior private bankers not to go to the US.

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