In eight countries, the iPhone X already accounts for over 2% of the iPhone active installed base just three weeks after its first availability on November 3. The leading countries for iPhone X adoption are markets with high gross domestic product (GDP) per head such as Singapore, Denmark, Switzerland and Japan, according to IHS Markit.

Countries where "Plus" model iPhones have been successful in the past have a strong correlation with initial levels of iPhone X adoption, the research firm noted. Consumers in those markets have a greater interest in larger displays and high-quality dual cameras, as well as the willingness to pay the higher price a Plus model or iPhone X costs over regular-size iPhones.

Despite production constraints, in the markets where iPhone X has launched, initial uptake is very similar to adoption of previous iPhone flagship launches in the same launch period. This indicates good demand for iPhone X and is better than the rumored supply, according to IHS Markit.

In the US, iPhone X adoption after three weeks matched the adoption of iPhone 8 Plus and beat early adoption levels for both the iPhone 8 and 7 Plus. Only the iPhone 7 model had greater initial success. In Japan, initial iPhone X adoption was as good as or better than any recent iPhone launch, and matched the level of the iPhone 7.

Apple will enjoy record-breaking iPhone performance in 2018

IHS Markit expects Apple to enjoy its best ever year for iPhone. IHS Markit forecasts each of the next four quarters will see on-year increases in iPhone shipment volumes.

In the fourth quarter of 2017, IHS Markit forecasts Apple will ship 88.8 million iPhones - this will be the greatest number of iPhones ever shipped in one quarter.

Apple will need to ship just 31 million iPhone X units for iPhone average selling price (ASP) to exceed US$700 for the first time in the iPhone's 10-year history, assuming total shipments amount to 88.8 million.