Apple may have sold a greater mix of the iPhone 6 Plus compared to the smaller and lower-priced iPhone 6, which means the company probably enjoyed strong margins during the December quarter. Susquehanna Financial Group analysts increased their estimates for Apple based on their checks of iPhone sales mix.

Apple Inc. - AAPL's Margins To Benefit From iPhone 6 Plus Sales

However, they lowered their unit numbers for the March quarter because they believe some iPhone 6 and iPhone 6 Plus sales were pulled into the December quarter.

Where Apple stands on iPhone 6, 6 Plus sales

In a report dated Jan. 14, analysts Chris Caso and Liz Pate said their checks suggest that production of the iPhone was higher in the December quarter. They’re now estimating that between 68 million and 73 million iPhones were produced during the quarter.

Their previous production estimate was for between 60 million and 65 million. They believe about 88% of the December quarter production was the iPhone 6 and iPhone 6 Plus, compared to their previous estimate of 80%.

A richer iPhone 6 mix

The Susquehanna analysts added that they think Apple enjoyed a “richer mix” of the more expensive iPhone 6 Plus models. In addition, they say the lack of a 32-gigabyte iPhone 6 probably helped boost Apple’s margins further because consumers who would have bought a 32-gig model probably opted for the more expensive 64-gig model instead.

The analysts estimate that Apple shipped 71 million iPhones during the December quarter, compared to their previous estimate of 61 million. The consensus estimate is around 66 million. They believe iPhone 6 Plus shipments were about the same as iPhone 6 shipments. Additionally, they think the mix of iPhone 6 Plus to iPhone 6 models will remain permanently better than they previously thought it would be.

For the March quarter, the Susquehanna team is estimating production of about 40 million to 50 million iPhones. They estimate shipments of 48 million iPhones compared to their previous estimate of 51 million. The consensus estimate for shipments in the March quarter is 52 million.

They continue to rate Apple as Positive with a $135 per share price target. Shares of Apple slipped as much as 0.6% during regular trading hours today.