SAN FRANCISCO (Bloomberg) - Apple Inc. unveiled a new version of the iPhone that boasts a bigger screen, faster chip and access to speedier wireless networks, an overhaul aimed at widening its lead over Samsung Electronics Co. and Google Inc. in the $219.1 billion smartphone market.The thinner, lighter device is called iPhone 5 and costs $199 to $399. It sports a casing made of glass and aluminum, a chip that can process commands more swiftly and a four-inch screen - compared with 3.5 inches on the earlier models. Apple also revamped its mobile software, adding three-dimensional mapping, closer integration with Facebook and improvements on the Siri voice-recognition feature.Coming almost a year after the death of Apple co-founder Steve Jobs, the next iPhone is the first hardware redesign of the product since 2010. After popularising handheld touch-screen devices that offer swift Web downloads and a range of games, entertainment and productivity tools, Apple is seeking to stay ahead of competitors including Samsung, Google, Microsoft and Nokia in a market that surged 78 percent last year.The iPhone 5 “is positioned to be a top seller, given the compelling new features, including the bigger screen and faster wireless speeds”, said Shaw Wu, an analyst at Sterne Agee & Leach Inc. The announcement contained few surprises, “given all the speculation” about the device, he said.Shares gained less than one percent to $664.05 as of 2.13 p.m. in New York, extending the surge that lifted Apple stock 63 percent this year through yesterday.Because Apple only introduces one new iPhone a year, each unveiling is critical. Apple has sold more than 244 million units since its 2007 debut, and the handset now accounts for about two-thirds of profit. Its popularity has led investors to catapult Apple’s market value to above $620 billion, making it the world’s most valuable company.“They have built a juggernaut,” said Matt Murphy, a partner at Kleiner Perkins Caufield & Byers, a venture capital firm that invests in iPhone application companies. “This is going to be an absolutely blowout, homerun product.”The new iPhone, Apple’s sixth since 2007, works with so- called long-term evolution, or LTE, data networks being introduced by companies including AT&T Inc. and Verizon Wireless. Samsung and Google’s Motorola Mobility are among the manufacturers that have already introduced handsets that run on LTE, which carriers say enables quicker video, music and other content downloads, compared with the existing wireless networks.By adding a bigger screen, Apple also is following a trend started by other handset makers, including Samsung, HTC Corp. and Motorola Mobility.The new iPhone software will feature tighter integration with Facebook, letting users quickly post pictures, links and other content to the world’s largest social network. The partnership is similar to one announced last year with Twitter.Apple also enhanced the speech-command service Siri, adding features that let users search for sports scores and make dinner reservations by speaking to the smartphone.IPhone 5 goes on sale on September 21 and is available for pre- orders tomorrow. Apple may sell 10 million iPhones by the end of September, according to Gene Munster, an analyst at Piper Jaffray Cos.