Holiday sales, iPhone inventory key for Apple: Pro

The two catalysts for Apple going into the end of the year are how holiday sales play out and inventory levels, Piper Jaffray's Gene Munster said.

"If (iPhone) inventory remains tight throughout the quarter I think there are going to be greater expectations about a 'guideup' in March," Munster told CNBC's "Fast Money". Piper Jaffray has a "buy" rating on Apple.

In the firm's weekly survey of about 80 stores, Munster said that inventories of iPhones are about 50 percent, which is "really tight" and "very positive for the gross margins in the March quarter."

Another edge Apple has is the larger screen size of the iPhone 6.

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"There's a big part of the market they haven't tapped into," Munster said. "The sustainability of this cycle I believe is going to last beyond the March quarter into the June quarter. And if they do that, that may shift the whole paradigm of how they address their addressable market."