He further added, North America is a priority for Nokia […] because it is a key market for Microsoft.[14] On 26 October 2011, Nokia unveiled its first Windows Phone 7-based devices, the high-end Lumia 800 and the mid-range Lumia 710, at its Nokia World conference.[15][16] After this announcement, Nokia's share price fell about 14%, its biggest drop since July 2009.[17] Nokia's smartphone sales, which had been increasing, collapsed.[18]