ONE of America’s leading activist funds, Harris Associates, has secretly built a $1 billion stake in UBS, the Swiss investment bank under fire from shareholders over its underperformance.

The Chicago-based fund manager – which controls $73 billion (£35 billion) and is best known for ousting the Saatchi brothers from the Saatchi & Saatchi advertising agency in 1994 – has built a stake representing nearly 1% of UBS over the past three months.

It is thought that Lansdowne Partners, one of the UK’s biggest hedge funds, managed by Stuart Roden and Peter Davies, has also built a significant stake.

UBS has faced calls from investors and analysts to split its wealth management and investment-banking divisions as a way of improving efficiencies and unlocking value.

The bank has been criticised for poor performance, particularly as a result of the failure of Dillon Read Capital Management, the hedge-fund business started by star trader John Costas in 2005. Two weeks ago, Peter Wuffli was ousted as chief executive. Analysts expect second-quarter results will be poor too.

The break-up calls have gained support following the spectacular results of TCI, the London hedge fund, in agitating for the break-up of ABN Amro.

But one analyst said: “Although it’s easy to say UBS is another ABN, that’s not the case. There are far more compelling reasons for UBS to remain whole than there were with ABN. The stock is attracting hedge funds simply because it has been oversold following the problems.”

Harris, which is run by David Herro, has also built a stake in Carpetright, the British retailer.

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