Apple shares were downgraded to sector weight from overweight by technology-focused research firm Pacific Crest.
Analyst Andy Hargreaves told clients to buy Alphabet shares with the money raised by selling some Apple stock.
"We believe AAPL anticipates strong performance in the iPhone 8 cycle, while providing relatively little weight to risks through the cycle or the potential for iPhone sales to decline in FY19," Hargreaves wrote in a note to investors Sunday. He cited risks "around gross margins, elasticity, supply issues, or the likelihood for declines beyond the iPhone 8 cycle."
This is just the fifth hold rating on Apple, according to analyst ranking site TipRanks.com. Twenty-five other analysts have a buy rating on the stock. None says sell.
Apple share prices were down about 1 percent after Monday's opening bell. They are up 33 percent this year and hit an all-time high in May as investors clamored into a few big technology stocks. Hargreaves predicts the stock will be $10 lower, to $145 a share 12 months from now.
The downgrade comes at the start of a big week for the iPhone maker. Its developers conference — WWDC — begins Monday where a new mobile operating system is expected to be unveiled. Most analysts expect the iPhone 8 will be released this fall, its usual time period for the release of the new phones.
But Hargreaves also became the latest analyst to mention some supply constraints that may limit the number of iPhone models that will be released for sale this year.
"Recent supply checks suggest iPhone 8 (OLED) may be delayed until October with limited initial supply that ramps through F1Q. Consequently, we are shifting iPhone units out of FY17 into FY18, which, along with an increase to our iPhone 8 ASP estimate, drives our FY17 EPS estimate down to $8.86 and our FY18 EPS estimate up to $10.53."
During Monday's premarket, Google was up about 0.9 percent
"We recommend large-cap tech investors use proceeds from sales of AAPL to purchase GOOGL (Overweight, PT $1,100), which we believe retains an excellent risk/reward profile and more substantial upside potential than AAPL," the Pacific Crest note said.
— With reporting by CNBC's Michael Bloom
Correction: This story was revised to correct that Apple's all-time high was in May.