While Apple's head of operations, Jeff Williams, has called the response to the Apple Watch "fantastic," analyst Alex Gauna said the wearable's debut has been "less than spectacular."
Williams' comments came during the second annual Code Conference in Rancho Palos Verdes, California, on Wednesday. However, he would not cite specific numbers.
While analysts at JPMorgan are predicting the tech giant will sell 36 million watches in the first 12 months, Guana thinks the figure is closer to 15 million.
"What we have is sources in the supply chain that suggest there were supply constraints as we started the ramp of this and then we're not yet in holiday season," the senior analyst at JMP Securities said in an interview with CNBC's "Closing Bell."
"We think that's why there's been a rather lackluster start to the Apple Watch sales."