It fell Friday morning after Morgan Stanley predicted that the company's iPhone sales will fall nearly 10 million below Wall Street's forecast.

The stock was the worst-performing in the Dow Jones industrial average and ultimately closed down 4 percent. That left the stock off 2 percent on the year.

The stakes are high for Apple as it fights to keep its place as the most valuable public company in the business world.

The iPhone giant reports quarterly earnings on May 1, by which time iPhone X sales should be baked in to its results. Apple doesn't usually release sales numbers of individual models.

The phone — the company's priciest yet — was widely expected to be a hit in the year ahead of its launch, with rumors of a new 10th-anniversary design and a "super-cycle" of upgrades. The company said in the autumn the phone was quickly backlogged, and CEO Tim Cook told CNBC that manufacturing was going well.

But enthusiasm seemed to nosedive after the iPhone X was released later in the holiday shopping season and undercut in price by the iPhone 8 and iPhone 8 Plus, both impressive in their own right. Apple executives have tried to reassure Wall Street, but recent reports have swayed sentiment.

In particular, Taiwan Semiconductor Manufacturing said Thursday that its revenue guidance range for the second quarter is $7.8 billion to $7.9 billion versus the Wall Street estimate of $8.8 billion. The chip maker counts Apple as a major client, leading some analysts to believe that Apple is to blame for TSMC's weak outlook.

But while Apple shares are down 2 percent year to date, 63 percent of analysts listed in FactSet still rate it as "overweight" or "buy." The average analyst expects shares to hit $192.84 for the year, well above Friday's close of $165.72.

Some analysts are still optimistic that Apple's repatriation of foreign cash and quickly growing services division could boost the business long term. Piper Jaffray analysts also said earlier this month that more teens than ever own iPhones, for example, which could grow even more if prices fall.

"Overall, we view the survey data as a sign that Apple's place as the dominant device brand among teens remains intact," Piper Jaffray's Michael Olson wrote. "We believe lower-cost 'X-gen' options would be well accepted by teens given strong mindshare Apple has with this demo."