Guggenheim analyst Robert Cihra downgraded Apple (AAPL) to Neutral from Buy and removed his prior $245 price target for the shares. The stock closed yesterday down $1.94 to $192.23.

The average selling price of the iPhone has increased a "dramatic" $220, or 40%, over the past 10 years, reflecting its "growing value to both consumer and business markets," Cihra tells investors in a research note. The analyst points out, however, that nearly half of that increase came in fiscal 2018 alone. This makes a "period of digestion now likely," Cihra writes in a note partially titled "ASPs No Longer Enough."

The analyst believes Apple's growth via average selling price is now "widely known." The iPhone's nearly 60% contribution to revenue and profits is "looking like a headwind again," says Cihra.

Following early supply chain cuts, exemplified by Corning's (GLW) "softer" Q4 gorilla glass guidance back in October and this week's warnings from 3D sensing laser supplier Lumentum (LITE) and LCD supplier Japan Display, the analyst now estimates iPhone units will decline 5% year-over-year in fiscal 2019.

He cut his fiscal 2019 earnings per estimate for Apple to $12.97 from $13.41 and revenue estimate to $273B from $281B.