Polycom (PLCM -4.2%) slumps following news China's Huawei is planning a major push into the high-margin telepresence videoconferencing market, with the goal of overtaking Cisco (NASDAQ:CSCO) as the market's #1 vendor. Polycom and Cisco are already struggling with poor demand for their videoconferencing gear, partly due to competition from software-based solutions, and Huawei, known for aggressively undercutting Western rivals, could pressure both the companies' sales and margins.