Apple stock has fallen this week as analysts add considerations of Mac unit sales to the recent iPod-fuelled stock value frenzy.

Banc of America analyst Keith Bachman warned yesterday that Apple's shares may have reached the upper limit of value at present, because of weak G5 sales.

"We believe G5 sales are the single-best gauge of the growth potential of Apple. The G5 is more important than the iPod in terms of profit impact," he wrote.

Bachman believes the stock should carry a value of $23.50, and gives it a neutral rating. He estimates Apple will ship 195,000 G5s in the current quarter.

Wall Street isn't in consensus. For example, Standard and Poors analyst Megan Graham Hackett rates Apple at Hold. While Apple has admitted it won't meet its 100-million-song download target, the analyst says: We see little profit impact from the expected shortfall since Apple largely provides the service to help spur sales of its iPod music device, which (the analysts) think continues to sell well". Apple is "fairly valued", the analyst says.

As Apple trades at its highest level for years, many analysts are articulating their opinion on the company. Schaeffer's Investment Research wrote: "iTunes continues to assert itself as the prime location for digital music." The report described the Apple's music service market popularity as "scoring a notable victory over any and all of its competitors."

While Prudential Financial analyst Steve Fortuna rates Apple a neutral with a $22 price target, UBS upgraded its assessment on Apple from neutral to buy with a $28 target on Monday.