Apple's dependence on the iPhone for revenue could hurt the company as the smartphone market approaches a period of structural change, BGC Partners' senior technology analyst told CNBC on Wednesday.
Colin Gillis recently put a $115 price target on shares of Apple, about $16 below where they are trading on Wednesday. The stock is up roughly 74 percent over the last year.
"If we are not at the top, we may be close to the top," he said in a "Squawk on the Street" interview.
Gillis acknowledged there is little that will pull down Apple's stock price in the near term, but he sees three trends impacting the tech giant's biggest sales driver.
Growth in the smartphone market is set to moderate from 20 to 30 percent to about 5 to 10 percent, the rate of expansion for the overall phone market, he said.
That outlook aligns with the forecast for smartphone shipments from global research firm IDC. It expects shipments to increase by 12.2 percent in 2015, compared with 26.3 percent growth in 2014.
Gillis also expects consumers to wait longer to upgrade their phones as they grow less enthusiastic about new features.
Finally, he sees the risk of wireless carriers becoming less willing or able to subsidize the cost of handsets, which will be a negative for Apple.
"If you're taking a longer-term view than the current quarter, you have to be aware that Apple's profit comes materially from the iPhone—70 percent of revenue, even more—and these dynamics of this industry are changing and that's undeniable," he said.
Apple should develop and grow revenue-generating services tied to its mobile products, Gillis said. He contrasted its strategy of reaping healthy margins from its high-end handset with Google's play to saturate the market with phones operating on its Android system, drive down prices and monetize with services.
As of the third quarter of 2014, Apple's iOS accounted for 11.7 percent of the smartphone market, while Android controlled 84.4 percent, according to IDC.
"If you had to give the iPhone away right now, Apple's revenue would be just a small fraction of what it is right now," he said.
The company recently broke into the electronic transactions market with Apple Pay. Robert W. Baird analyst Will Power recently told CNBC the service accounts for two-thirds of all mobile payments in the United States since launching in October.
However, he said it only accounted for a very small share of Apple's revenue, perhaps 2 percent.
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