Analysts at Wall Street are beginning to moderate their views on Apple's financial outlook, with concerns that the popular iPhone may be at its peak profit margin and that growing sales of the iPad with the launch of a smaller version will impinge on the company's overall gross profits.

Andry Hargreaves, analyst at Pacific Crest Securities, has published a research note in which he has trimmed his target for the tech giant's share price to $645 from $670, citing his belief that higher costs of goods sold for the iPhone 5 will push Apple's overall gross margin to 38.8% from the usual 40% it normally maintains for its devices.

"Declining gross profit dollars per iPhone and volume sales of iPad are driving lower gross profit per unit of Apple product sold," Hargreaves said, adding that "exceptional unit volume is required to maintain growth at Apple."

Hargreaves believes that Apple's gross profit dollars per unit "has likely peaked" after estimating the cost to produce each device going up to $370 from $353, causing the margins to be squeezed.

Betweem 2007 until Q2 2012, Hargreaves says iPhone unit growth and margin expansion drove Apple's gross profit per unit to $290 from less than $150. That increase in gross profit per unit has driven around a third of Apple's total gross profit growth over that period, but in Q3 gross profit per unit fell for the first time since the iPhone was introduced. Hargreaves says the total is likely to decline further through the end of the fiscal year 2013.

The Pacific Crest report follows a month of bad news from analysts regarding Apple's market position.

At the start of November, IDC said that Apple's share of the tablet market has shrunk from 59.7% last year to 50.4% today, sighting Android devices from the likes of Samsung, Amazon and Asus, moving in to take a larger slice.

That report was followed by comments from Global Equities Research analyst Trip Chowdry who said that innovation at Apple was "sputtering."

"Why is that Apple, the company that brought touch to phones and tablets, stopped just there and did not bring touch to notebooks and iMacs? Why is it that Apple brought high-resolution screens to some MacBooks and not to all devices? High-resolution screens are a commodity today," said Chowdry.

Apple grew to be the biggest company in the world by market capitalisation under its innovative CEO Steve Jobs. However, since his death from cancer last year, analysts have questioned whether the company could continue its leadership in the field of consumer technology.

Hargreaves' cautionary message follows another report released on Monday by Citi Research which warns that the risks for Apple "are increasingly coming into focus."

"We assert that Apple's share of the smartphone market is at risk from low-end smartphones and competition from other ecosystems," said Citi. "We see upside from tablets, but this negatively impacts (gross margins)."