IPhone 4S announced iPhone 5s and iPhone 5c. This was unusual for Apple as an upper case 'S' had been used since the introduction of the iPhone 3GS in 2009. On September 9, 2014, the iPhone 4S was officially discontinued following the reveal of the iPhone 6 and the iPhone 6 Plus. However, 4S production did continue for developing markets until February 17, 2016. On June 13, 2016, following the release of iOS 10, Apple dropped support on the iPhone 4S, making iOS 9.3.5 the last version available for the device. The runs iOS, Apple's mobile operating system. The user interface of
IPhone 5S 5S "is not a required upgrade, but it's easily the fastest and most advanced Apple smartphone to date." Although praised for its camera, 64-bit A7 chip, M7 motion-chip, and fingerprint scanning capabilities, some investors thought that the iPhone 5S, although a notable improvement over the iPhone 5, was still relatively unchanged from its predecessor, and worried that the iPhone line had become a stagnant, dull product. Apple's share price fell 5.4% after the launch to close at a month low of $467.71 on the NASDAQ. Darrell Etherington of TechCrunch who praised the iPhone 5S as the best smartphone available said