Apple (NASDAQ:AAPL) shares have enjoyed a tremendous run year-to-date. In that time, the stock is up nearly 40%, which is particularly impressive considering that a 40% increase in the company's stock price means that Apple's market value grew by north of $200 billion.

This rise is almost certainly due in large part to the enthusiasm for Apple's upcoming trio of iPhones, which the company is expected to unveil at a special event on Sept. 12, and the potential impact that they could have on Apple's business.

Apple's iPhone 7 Plus in Jet Black.

Image source: Apple.

To illustrate just how important the iPhone is to Apple's business, iPhone sales made up 63% of the company's net revenue in its fiscal year 2016.

Though Apple's current stock price seems to bake in a successful iPhone cycle, here are three reasons Apple shares could rise further following the unveiling of the new phones.

Apple's expectations are big, but sales could be even bigger

There's evidence out there to suggest that Apple is keenly aware that the coming iPhone cycle could be huge.

Last month, analysts with BlueFin Research Partners claimed that Apple is planning to produce iPhones at record rates for the remainder of this year as well as the entirety of next year.

Build plans can shift with demand signals, however. There's risk that initial demand for the new iPhone models isn't as robust as Apple currently hopes, which could lead it to revise down its build plans.

On the flip side, if the initial sales data proves even more robust than even Apple expected ahead of the launch, then that could be a sign that demand throughout the entire iPhone product cycle will be better than Apple originally planned.

An increase in build plans is something that'll almost certainly leak out through either the press or the analyst community, and such news could push Apple shares up further.

Apple's other businesses could take off

Though Apple's iPhone business is by far the company's most important, success in its other businesses could help further fuel Apple's financial results and share price.

To be clear: If Apple's iPhone business disappoints, then it'd be extremely difficult for the rest of Apple's product portfolio to just make up the slack, let alone drive better-than-expected financial results.

However, if Apple's iPhone at least delivers to expectations, then strength from Apple's other businesses could accelerate the company's financial results.

The two businesses that I think have the most potential to surprise are Apple's Services business (which is now the company's second-largest), and the company's "Other" reporting segment which includes, among other things, sales of the company's surprisingly popular AirPod wireless earbuds and its fast-growing Apple Watch business.

Investors could get good news about the 2018 iPhone models

One of the worries ahead of the iPhone 6s product cycle was that Apple would have a hard time topping what was an epic iPhone 6 cycle, and those fears were certainly justified as iPhone shipments fell year-over-year during the iPhone 6s cycle.

I suspect that after seeing what happened during the iPhone 6s cycle, investors are going to be -- rightfully, I might add -- skeptical that Apple can grow iPhone shipments and revenue in the following product cycle.

That said, as the leaks come in detailing the 2018 iPhone lineup, investors should be able to quickly get a sense of whether Apple is planning a relatively incremental set of products, or if it's planning to release products that deliver exciting improvements over the iPhones that'll be announced shortly.

If it's the former, then I'd expect the skepticism to remain, but if signs point to the latter, then that could lead to increased optimism among investors for a second consecutive strong iPhone cycle, driving earnings expectations -- and therefore the stock price -- up.

Ashraf Eassa has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Apple. The Motley Fool has a disclosure policy.