Whether you want it to or not, Apple (NASDAQ:AAPL) is trying to change your world.

The tech giant that helped kickstart the PC and mobile revolutions has never lacked for ambition, and perhaps no initiative on the company's part better exemplifies its sweeping visions for the future than Project Titan, Apple's once-secret automobile effort.

But all is not necessarily well in Cupertino these days. According to reports, Project Titan appears to have hit its first major speed bump, which could threaten Apple's ambitious timetable for its next truly disruptive product.

Problems at Project Titan
According to a report from AppleInsider citing sources familiar with the matter, Apple has placed its Project Titan team under a hiring freeze after members of Apple's executive team grew concerned over the project's direction and progress.

The alarming decision stemmed from a progress review conducted by Apple design chief Sir Jony Ive upon returning from the holiday season in which the design guru reportedly "expressed his displeasure" with the team's lack of tangible progress. Though not definitively related, this move also probably coincides with the recent departure of Steve Zadesky, the longtime Apple veteran tasked to lead Project Titan whose resignation for "personal reasons" surfaced late last week. It doesn't take a genius to read between the lines.

Apple is reported to have expanded its staff for Project Titan to over 1,000 employees as it has attempted to bring Project Titan to market by 2019, an abnormally accelerated schedule for an industry where product cycles typically hover closer to seven years. And though the hiring freeze in and of itself isn't necessarily a negative, news of issues at Project Titan should concern Apple investors because of its long-term necessity for the company.

Why Project Titan matters for Apple Stock
If the past five years of its stock market history contain a single lesson, it's that Apple has suffered because of a lack of growth, not profits. And though Apple enjoys nearer-term growth catalysts, especially the coming iPhone 7 refresh, the company has grown so large that it can only achieve meaningful growth by disrupting massive markets -- such as the automotive industry.

The global auto industry was expected to surpass 88 million total sales in 2015, according to researcher IHS, making it one of the few multitrillion-dollar consumer markets that could still provide Apple the opportunity to double sales without capturing the majority of its market share. Contrast Apple's automobile market with the global watch market, and the necessity for Apple to place increasingly big bets to drive returns becomes evident.

According to estimates from Bloomberg, the global watch industry produces sales of roughly $60 billion annually. True, the industry's gross margins of nearly 60% make it a highly complimentary market for Apple's traditional high-margin consumer electronics. However, the entire industry's annual sales represent about one-quarter of Apple's expected FY 2016 revenue.

Apple needs to target massive markets to continue to meaningfully expand its financial footprint, which is why Apple investors will want to closely monitor the apparent struggles at what one could argue is Apple's most important strategic initiative today.

Andrew Tonner owns shares of Apple. The Motley Fool owns shares of and recommends Apple. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.