Just how high can Apple go?

Apple shares soared to an all-time high of $100.77 on Wednesday as investors eagerly await the release of its next generation iPhone. Or, at least, it seems that's what the hope is.

The technology company will hold a media event on Sept. 9, where it will likely unveil its latest iPhone and possibly an iWatch device, according to published reports.

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Apple logo store
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It's not unusual for Apple's stock to rally ahead of a product announcement, Steve Milunovich, managing director at UBS, told CNBC on Wednesday.

But will Apple's stock continue to climb after the product announcement? Only time will tell.

Shares fell when the company had unveiled the iPad and later the iPhone 5 to a weak reception, Milunovich noted. But "this time is different," he said.

Between the possibility of the latest iPhone and even an iWatch, Milunovich maintains a "buy" rating on the stock and thinks it could go to $115 a share, roughly a 15 percent premium from current levels.

"The new phones are going to be addressing a third of the market that Apple does not address today," Milunovich said on "Squawk Alley." "They've not played in in larger screen phones, suggesting you could have a very strong upgrade cycle that we still think could be more people expect."

Milunovich has "relatively conservative expectations" for the iWatch because he thinks the iPhone will be "the main event." Still, he noted most analysts have not factored the iWatch into their price target models.

Jean-Louis Gassée, former president of Apple's product division, wouldn't speculate on what Apple might announce. He did, however, say an iWatch is unlikely to "move the needle."

"They have one and only one business: personal computers," Gassée told "Squawk Alley" on Tuesday. "These come in three sizes: small, medium and large; smartphones, tablets, and PCs—desktops and laptops—and everything else supports that business in an ecosystem."

The "sweet spot" for Apple is the balance between PC and tablet devices, Gassée said.

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—By CNBC's Drew Sandholm