There's little question that Apple (AAPL -1.82%) lives and dies by sales of the iPhone. The company has worked diligently in recent years to reduce its reliance on its flagship device by pushing heavily into services and wearables. But because of the iPhone's sheer dominance and despite Apple's best efforts, much of the company's fortune rests on the success or failure of this single product line.

That's likely good news for Apple investors this year, as the company seems poised to break its all-time holiday sales record with brisk sales of the iPhone 13 heading into the all-important end-of-year shopping season. But global supply chain issues could put coal in Apple's stocking.

Senior person looking at a smartphone in the kitchen with a Christmas tree in the background.

Image source: Getty Images.

A telling indicator

Long and growing delivery times for the iPhone have historically been a pretty good gauge of strong demand, giving analysts' and investors alike insight into sales of the iconic device. Wedbush Securities analyst Dan Ives has put pencil to paper and concluded that demand is outstripping supply by roughly 15% ahead of Black Friday when the holiday shopping season begins in earnest. 

"We estimate that Apple is on pace to sell [approximately] 40 million iPhones between Black Friday and Christmas," Ives wrote in a recent note to clients, "which would be [a] record holiday pace for the company." Ives cited channel checks that suggest "tremendous demand trends" across the U.S. and in China as evidence that Apple could sell more than 80 million iPhones during the holiday quarter. To put a bow on this holiday package, Ives sees strong demand for pricier "Pro versions driving higher ASPs [average selling prices]."

But there's a catch

The news isn't all good, however. Global supply chain issues have been making headlines for months, with no relief in sight. President Joe Biden stepped in, announcing that the Port of Los Angeles would join the Port of Long Beach in operating around the clock to help clear the logjam of ships waiting to unload goods and supplies. There also remains a shortage of shipping containers and truck drivers to transport them. 

Ives acknowledges the "chip shortage and Rubik's Cube logistics that Apple (and every other technology, auto, and retail vendor) is dealing with." But he remains undeterred, saying he expects record sales "despite the lingering chip shortage limiting iPhone supply globally by roughly 10 million units based on our analysis."

Two rose colored iPhone 13s resting diagonally showing front and back view.

Image source: Apple.

Spreading holiday cheer for investors

Ives isn't the only one spreading holiday cheer. Morgan Stanley analyst Katy Huberty studied Apple's most recent regulatory filings and detected a 25% increase in inventory held by the company's manufacturing partners. Huberty concludes that a larger number of iPhones in the pipeline is indicative of stronger demand. 

If these analysts are right, it certainly bodes well for Apple investors. The company closed out fiscal 2021 (ended Sept. 25, 2021) with record sales of the iPhone, helping push the stock -- and Apple's market cap -- to a new all-time high.

He's a mean one, Mr. Grinch...

Only time will tell whether the global supply chain crisis will be the Grinch that tries to steal Apple's Christmas cheer. It's important to remember, however, that one quarter is hardly enough time for an investing thesis to play out.

For fiscal 2021 (ended Sep. 25, 21) Apple's revenue of $365.8 billion grew 33% year over year. At the same time, iPhone sales of $192 billion climbed 39%, representing 52% of Apple's total revenue. This shows that this single device still drives much of Apple's fortunes. 

Furthermore, the iPhone is likely in the midst of the much-ballyhooed 5G supercycle, as an estimated 25% of Apple customers have not upgraded their iPhone over the past three and a half years. With more than 1 billion active iPhones worldwide, that suggests as many as 250 million iPhone users could trade in their old device for a new one in the coming months.

When viewed through the lens of its ongoing potential and persistent demand, investors should definitely consider putting some Apple stock under their tree.