The iPhone X is so popular that it just might wind up hurting Apple down the road.
It has been so successful that more and more iPhone users are upgrading early, eating into demand for future generations, according to New Street Research.
The vacuum in sales will be so great that investors should sell the stock, analyst Pierre Ferragu said in a note Monday.
"We expect a material disappointment in 2019," Ferragu said. "The iPhone X has been very successful and well received by consumers. It has been so successful, that we think it has brought forward demand."
IPhone users upgrading early "will drive an 'air pocket,' and the introduction of a lower-price premium OLED phone won't be enough to make up for the shortfall," the analyst added.