Shares in Apple Computer have soared by 11 per cent to a four-year high after hopes for the success of the iPod music player prompted a technology analyst to double his target for the stock.

Gene Munster, the Piper Jaffray analyst, raised to $100 from $52 his goal for the shares on research showing that the iPod, of which 6 million have been sold in three years, was having a "halo effect" in boosting demand for other Apple products.

A second analyst, Robert Chihra of Fulcrum Global Partners, raised his target to $65 from $53.

A Piper Jaffray survey showed that 6 per cent of 200 iPod users surveyed had switched allegiance from PCs – the Microsoft-friendly computer set-up - to Apple Macintosh products.

A further seven per cent said that they intended to buy a Mac within the next 12 months.

"We believe that the remarkable satisfaction with the iPod creates a word-of-mouth wildfire that generates new customer interest in Apple products," Mr Munster said.

While many observers have speculated over a "halo effect" from the iPod, of which 6 million have been sold in three years, Mr Munster's report was treated with caution by many sector experts.

Roger Kay, an analyst at IDC, the research company, said: "To confirm that kind of data, it seems like one study isn't enough to draw a conclusion."

Mike McGuire, at GartnerG2, said that the survey was based on "kind of a small sample".

However, Apple stock surged by $6.18 to close at $61.35, hitting $64 at one point, and remained firm in after-hours trading. The stock has risen by about 150 per cent this year.

Apple shares have not hit $100 since June 20 2000, the day before Apple executed a two-for-one stock split.

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