A mockup of a HTC Butterfly smartphone (left) and a Desire C smartphone are displayed in a mobile phone shop in Taipei. HTC Corp forecast its sixth consecutive decline in quarterly sales as the Taiwan-based smartphone maker faces a loss of market share to Chinese mainland rivals. First-quarter revenue will be NT$50 billion (US$1.7 billion) to NT$60 billion, the company said in a statement yesterday. HTC fell out of the global top five by smartphone market share last quarter as Samsung Electronics Co, Huawei Technologies Co and ZTE Corp gained shares.