Two-thirds of the most affluent Americans use computers to research investments, while almost a third trade online, a new survey revealed yesterday. The findings will intensify concern over the future of traditional stockbrokers in the US following last week's announcement that Merrill Lynch, the largest US retail broker, was launching an online trading service.

The analysis, sponsored by US Trust, a large private bank catering to the wealthy, covered a sample of the most affluent 1 per cent of Americans. Each has a gross annual income of at least $225,000 (€215.455) and a net worth of more than $3 million.

These people represent the most lucrative business for private banks and for full-service brokers such as Merrill Lynch and PaineWebber. The survey shows even the wealthiest are taking advantage of the Internet to research stocks for free, and to trade at low cost.