Though Intel Corporation (INTC 1.77%) is one of the world's most successful technology companies, the slowdown of the PC market over the last several years, coupled with repeated misfires in trying to attack the mobile market, have served to cast doubt on the long-term growth profile of the company.

While things have gotten a lot better for Intel recently, it's important for investors -- both bulls and bears -- to understand what risks the company (and therefore the stock) faces. Commensurate with that perspective, here are three reasons that Intel's stock could fall from current levels. 

PC sales still uncertain post-XP refresh
The biggest driver for the recent strength in Intel's PC business has been the growth in sales of business-oriented PCs, which often use higher priced, higher margin processors from Intel. Bears argue that once the Windows XP refresh subsides, Intel is likely to see a slowdown in business PC sales -- potentially leading to a weaker 2015 for the company's PC chip sales (which comprised about 63% of the company's sales in 2013). 

Additionally, while the business PC market is strong, CEO Brian Krzanich referred to the consumer segment as "challenging". It's stabilizing in mature markets such as the United States, but in the Asia-Pacific region (which is one of Intel's most important geographic regions), consumer PCs are still weak -- in no small part due to the proliferation of inexpensive tablets.

If the business PC demand ultimately turns out to be an unsustainable bump up, and if consumer PC demand deteriorates further, then this could lead to a continued downtrend in the company's large and lucrative PC chip business.

Intel could keep fumbling mobile
There's very little doubt that the mobile revolution has fundamentally changed computing. The iPhone 5s, for example, offers similar computing performance to a 2010 MacBook Air, and with software developer attention increasingly focused on mobile applications (thanks to a very large smartphone and tablet installed base), these mobile devices will only become more capable with time.

That's a problem for Intel.

For years, Intel has been talking about becoming a major player in mobile, but its mobile group has yet to deliver. Some of the issues plaguing the division boil down to Intel defining and building the wrong products for its intended markets, and others boil down to correctly defined products that simply made it out too late. 

All told, Intel's mobile business is burning over $4 billion per year at the current run-rate, and continued missteps here could mean that these losses will remain elevated, diluting the successes of Intel's other businesses.

Good mobile execution may not be enough
One of the big risks to Intel's business is that even if its mobile execution becomes first-rate, it faces fundamental business model headwinds. For example, Apple (AAPL 0.52%) and Samsung (NASDAQOTH: SSNLF) -- which combined own nearly half of the smartphone market -- have in-house processor development teams. 

Though Apple is unlikely to ever use an Intel-designed chip for its iOS devices, some rightfully argue that Samsung uses chips from external vendors such as Qualcomm. While this is true, note that Samsung also seeks to build chips for companies that don't have their own manufacturing plants (known as "fabless" semiconductor companies).

It wouldn't be a stretch to assume that if Samsung used external chips, it would prefer to use those chips if they are built by Samsung's chip manufacturing plants than by a competitor's.

The upshot is this: If Samsung and Apple see their combined market share of the smartphone (and, to a lesser extent, the tablet) market decline, then Intel has more opportunities to fight for mobile market share. If this doesn't turn out to be the case, then Intel -- even with a strong product lineup -- may have a tough time actually selling its products in the volumes needed to recoup its investments in the mobile business.

Foolish bottom line
At the end of the day, Intel is a great company and its stock has rewarded shareholders handsomely over the last year. However, no company is perfect, and Intel still faces a number of execution and secular risks.

This doesn't necessarily mean that Intel's stock is going to drop over the next year, but these are some of the key arguments that those who do believe Intel is poised to fall are banking on.