Leading smartphone vendor HTC on Wednesday trimmed its fourth-quarter revenue forecast by roughly 23% as stiff competition from Samsung and Apple has seeming slowed sales. The Taiwan-based company became the No.1 smartphone vendor in the U.S. by shipment volume last quarter, but a six-month string of record revenue came to an end in October following the release of Apple’s highly anticipated iPhone 4S. In light of the new iPhone and Samsung’s recent success in the smartphone space, HTC lowered its fourth-quarter revenue forecast to NT$104 billion from its earlier guidance of between NT$125 billion and NT$135 billion. Unless things pick up, HTC’s sales will decline sequentially for the first time in two years, Bloomberg reports. HTC said it will also reevaluate its $300 million acquisition of S3 Graphics following news that it lost a patent-infringement case against Apple earlier this week.