The world's most valuable company has surprisingly been left out of the impressive rally in the broader stock market to kick off 2018. 

Pin part of the blame on confusion among Wall Street analysts ahead of Apple's earnings on Feb 1. 

Apple (AAPL) - Get Report shares have shed about 0.4% year to date, lagging the Nasdaq Composite's 7% surge. The S&P 500 and Dow Jones Industrial Average have soared 6.5% and 7.2%, respectively. Apple's stock is the worst performer this year among the tech group commonly referred to as FAANG:

Most on Wall Street continue to voice concern on demand for Apple's pricey new iPhone X. Atlantic Equities analyst James Cordwell lowered his rating on Apple to neutral from overweight this week, noting that while the December quarter showed robust iPhone X demand momentum may not persist into 2018.

"We believe a major component of the likely strength in the December quarter versus consensus is the fact that iPhone X supply improved much more quickly than we (and the Street) had anticipated," Cordwell wrote. "This better than anticipated supply means that a greater proportion of demand was able to be served in the December quarter, leaving March quarter expectations (which were predicated on significant pent-up demand) for ~20% iPhone unit growth now looking somewhat aggressive (~20% iPhone unit growth)."

Meanwhile, Longbow analyst Shawn Harrison said the anniversary edition of the iPhone, which has a list price of $999, has seen "lukewarm" reception from customers and called the current cycle of overall iPhone sales "good, not great." Harrison also slashed his earnings per share estimate for Apple by 29 cents to $11.25 and pegged his fiscal year shipment forecast at 233 million units. Longbow's rating on the stock was reduced to "neutral" from "buy."

Not every analyst is downbeat on Apple though. Some continue to hold firm on the market not appreciating rising average selling prices on Apple's smartphones, lucrative service revenues and boost to earnings from tax reform. 

"Fundamentally, we think [earnings] upside [in the holiday quarter] will stem from better iPhone average selling price trends (both mix and memory tailwind), services growth/acceleration, and tailwinds from channel fill," says RBC Capital market analyst Amit Daryanani ahead of the results. "Our positive bias on Apple is driven by: (a) iPhone average selling prices enabling upside to revenues; (b) gross-margin upside from mix (more services and iPhone memory); (c) potential for lower tax-rate and buyback tailwinds, which should provide a path toward $14 plus earnings per share by fiscal year 2019; and (d) foreign exchange tailwinds.

Get ready to fire up those live Apple earnings day blogs ... this report will have its fair share of intrigue. 

-Martin Baccardax contributed to this story.

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