What happens to Apple stock if watch disappoints?

Apple Watch apps
Adam Jeffery | CNBC

Apple's stock may be near a top if earnings Tuesday after the bell reveal a watch flop.

This disappointment would call into question the tech juggernaut's ability to keep cranking out hit products, a crucial belief that drives huge growth expectations for the shares from investors and analysts.

Sales of iPhones could "drive up the stock price from here but I don't have an astronomical price target because it's tempered by things like the watch," said Brian Blair of Rosenblatt Securities, noting other pressure from slowing iPad sales and headwinds in the overall PC market.