Apple's smartphone market share is expected to peak this year, with arch rival Samsung increasing its lead by broadening onto new platforms. See: Smartphone reviews

Smartphone shipments will account for 50 percent of all handset shipments by 2014 and become the largest handset segment in the world, according to the latest market forecasts by market intelligence analysts at ABI Research.

By 2018, 2.4 billion handset shipments with smartphones will account for 69 percent of all handset shipments. 4G or LTE handsets, like Apple's iPhone 5, will account for 35 percent of all handset shipments and 50 percent of smartphone shipments in 2018. See: iPhone reviews

"Barring an unlikely collapse in Samsung's business, even Apple will be chasing Samsung's technology, software, and device leadership in 2013 through the foreseeable future," says senior analyst Michael Morgan.

Since 2010 Samsung has grown its smartphone market share from 8 percent to over 30 percent in 2012; meanwhile Apple's market share is expected to peak in 2013 at 22 percent; remaining flat through 2018.

While Samsung's rise has been on the back of Android, which accounts for 90 percent of Samsung's smartphone shipments, the future smartphone OS landscape will likely be heavily influenced by the importance Samsung places on the elements of its OS portfolio of Bada, Tizen, Windows Phone, and Android phones.

Just as handset OEM focus has driven the success of the Android ecosystem, LTE smartphones, and handsets will also experience a rapid increase in shipment penetration as handset OEMs battle to keep their handsets relevant to mobile operators.

As 4G/LTE handsets commonly feature the latest in screen and application processor technologies, LTE handsets will also benefit from the demand of consumers looking to acquire a premium smartphone regardless of its WWAN connectivity.

"With the successful launch of the iPhone 5 and competing LTE handsets from other leading OEMs, LTE handsets will be found in the hands of many consumers who do not even have access to LTE networks," adds senior practice director Jeff Orr.

"Apple is demonstrating to the market that LTE is not the only reason to buy a premium handset."

While LTE will be the fastest-growing WWAN technology in history, the growth in smartphone shipment penetration will be driven by the rapidly growing low-cost smartphone segment.

ABI Research forecasts that smartphones with wholesale ASPs under $250 will account for 62 percent of smartphone shipments by 2018.

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See also:

iPhone 5 orders cut in preparation for 'evolutionary technology leap' for iPhone 6, analyst

iPhone has outsold Samsung smartphones by 219 million to 131 million, analyst

Smartphone world to get new two new OSs in 2013