Apple (NASDAQ: AAPL) is lower again in early trade Tuesday (-0.4%) after supplier Dialog Semiconductor revised lower its revenue outlook for the fourth quarter. Dialog said it now expects revenue in the range of $390-$400 million, which compares to the prior guidance of $430-$460 million. Dialog specifically called out weakness Mobile Systems segment. Apple accounts for +75% of Dialog’s total revenue, or as much as 90% of the company’s Mobile System segment.

Stiel analyst Aaron Raker said the size of the Dialog miss leaves them to believe it is iPhone (vs. iPad) related, and based on the dollar content that Dialog would typically see, they believe investors could estimate as much as a 12 million unit shortfall.

"As a reference on the December quarter, we would note that we would find a high historical quarterly correlation (R2 = 0.945) between Dialog’s total Mobile Systems segment revenue and the comparable quarter Apple iPhone shipments," Rakers said.

He added, "Using an estimate that Mobile Systems accounts for ~86% of Dialog’s total revenue for the December quarter (average at 86.7% over the prior three years) – and while appreciating that this data will leave investors to question the trends looking into the March quarter – the historical comparable quarter correlation would leave us at a ~68-70M iPhone shipment level for the December quarter (vs. our 74.7M estimate). We also illustrate a historical correlation comparison between Dialog’s Mobile Systems revenue and total iPhone + iPad shipments (R2 = 0.923), from which a C4Q15 estimate would leave us at ~92-93 total shipments, in line with our estimate for the December quarter."

"While we would note that our tracking of December quarter data points has left us comfortable with our mid-70 million unit expectation (e.g., non-Android smartphone consumption at ~20% share in October + November vs. ~12% in C3Q15; China’s mobile phone export data tracking to +3% y/y in C4Q15, etc.), we have reported that November data represented a decline when compared to October for the first time in an Apple product cycle that we have seen over the past several years. We believe investors are still to gauge potential blended ASP ($/unit) upside for the December quarter. Dialog has positively preannounced results for the December quarter in three out of the past four years."

Stifel maintained a Buy rating and $150 price target on Apple.

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Shares of Apple closed at $112.48 yesterday.