A key indicator for iPhone sales has gone into decline

iPhone 7 will trigger an 8% growth in unit sales for Apple, according to UBS analysts Steven Milunovich and Benjamin Wilson. The pair's procurement sources in Asia show that Apple is preparing a supply of iPhone 7's that will be greater than that of the iPhone 6s but less than iPhone 6.

The UBS team believes that 44% of iPhone users in 2015 will upgrade into the iPhone 7 through 2017. Typically, 50-60% of users with an iPhone two or more years old upgrade in a given year - so the upgrade trend for iPhone 7 is still down. Apple already reported that iPhone sales went into decline by 15% in the quarter ended in July.

On top of that, search interest in the word "iPhone" is dropping off. On its own, that is merely cosmetic. But as people often begin their online shopping with Google, a decline in searches for iPhone could mean that fewer people want to buy the phone.

Highlights from the UBS note:

• "The UBS Asia tech team's latest estimates show iPhone 7 procurement plans for F17 have increased from 80mn to 89mn, mainly due to 7 Plus needs. This figure is higher than the iPhone 6s procurement of 87mn but lower than the 93mn for the iPhone 6, which fits with our thesis."
• "... the size of the installed base and the maturation of the F15 iPhone class should be enough to drive roughly 8% growth in iPhone units. We are currently assuming 44% of the F15 class upgrade in two years, down from the typical 50-60%."
• "... In developed markets, search volume for the iPhone 7 was greater than the 6s but below the 6 and the 5."

Historic US search trends for iPhone: