What happened 

Shares of Apple (AAPL -1.44%) declined on Friday, following the technology giant's fiscal 2021 fourth-quarter earnings results. By the close of trading, Apple's stock price was down 1.8% after falling as much as 4% earlier in the day. 

So what

Apple's revenue surged 29% year over year to $83.4 billion. "Our record September quarter results capped off a remarkable fiscal year of strong double-digit growth, during which we set new revenue records in all of our geographic segments and product categories in spite of continued uncertainty in the macro-environment," CFO Luca Maestri said in a press release.

Wall Street, however, was expecting even more. Analysts had forecast revenue of nearly $85 billion. iPhone sales, which climbed 47% to $38.9 billion, fell short of consensus estimates of $41.5 billion. 

A stock chart that declines and then stabilizes.

Apple's stock price pulled back on Friday. Image source: Getty Images.

CEO Tim Cook said during a conference call with analysts that supply chain issues -- including semiconductor shortages and coronavirus-related manufacturing delays -- dented Apple's sales by roughly $6 billion. 

Still, the tech titan's growing base of iPhones, iPads, and Macs helped to fuel a 26% increase in Apple's high-margin services revenue, to $18.3 billion. "The combination of our record sales performance, unmatched customer loyalty, and strength of our ecosystem drove our active installed base of devices to a new all-time high," Maestri said. 

All told, Apple's net income soared 62% to $20.6 billion, or $1.24 per share.

Now what 

Apple's shortfall relative to consensus estimates appears to be more of a supply issue rather than waning interest among consumers. "Demand was very robust," Cook said during the company's earnings call. 

So, any sales Apple missed during the fourth quarter may simply be delayed rather than lost, which could help to explain why its stock was able to claw back some of its earlier losses by the end of the trading day.