iPhone 5s NY Sept 2013
Alejandro de Rosa (R) and Melisa Racineti of Buenos Aires, Argentina pose with their new Apple iPhone 5s phones with Apple employee Jay at the Apple Retail Store on Fifth Avenue in Manhattan. Reuters

While Apple’s (NASDAQ:AAPL) new iOS 7 mobile operating system is gaining momentum as early adopters switch to the revamped platform, its latest phones -- the iPhone 5s and iPhone 5c -- appear to be selling well, with Localytics, a mobile and web app analytics firm, claiming that the new handsets account for nearly 1.5 percent of all iPhones in the United States, within three days of being released to the public.

According to Localytics, the iPhone 5s and iPhone 5c now represent 1.36 percent of all iPhones activated in the U.S. across the four leading carriers -- AT&T, Verizon Wireless, Sprint and T-Mobile.

In less than 3 days, the iPhone 5s and 5c combined now represent about 1.36 percent of the total numbers of all iPhones activated in the U.S. market across the top 4 carriers. Localytics

The data reveal that 1.05 percent of all iPhones in the U.S. are now iPhone 5s, while iPhone 5c models account for 0.31 percent of the market, indicating that early adopters are favoring the high-end version of the handset.

“This makes sense since those who feel the need to buy a new device the very weekend it launches are most likely the power users who want the highest-end phone experience,” a statement on Localytics’ website said.

International adoption of the iPhone 5s and iPhone 5c. Localytics

According to Localytics, a similar pattern has been noticed for international adoption rates of the new iPhones as well. Globally, sales of the iPhone 5s are 3.7 times more than that of the iPhone 5c. In some countries, the ratio is even higher. For example, in Japan, the iPhone 5s is outselling the iPhone 5c by a factor of five.

In addition, Localytics, which also monitors the handsets' overall adoption rates in other countries, shows that as of now, the U.S. continues to be the largest market for the new devices, accounting for more than twice the number of units sold in all other markets combined.

In terms of carrier adoption, in the U.S., AT&T has so far seen the highest adoption rates for both the iPhone 5s and iPhone 5c, representing 0.67 percent of all activated iPhones, compared to 0.51 percent for Verizon, 0.12 percent for Sprint and 0.07 percent for T-Mobile.

Localytics examined data from more than 20 million unique U.S. iPhones from the iPhone 5s and 5c release date on Sept. 20 through to 8 p.m. EDT, on Sept. 22.