Among the stock activity stories for Thursday, Oct. 1, from AP Financial News: NEW YORK (AP) ¿ Polycom Inc. shares fell as Cisco Systems Inc. ramped up competition in the video-conferencing market with its $3 billion acquisition of Norway's Tandberg ASA. NEW YORK (AP) ¿ Shares of Nvidia Corp. fell after a JPMorgan analyst downgraded the chipmaker, saying sales in its chipset business may suffer. SIOUX FALLS, S.D. (AP) ¿ Shares of ethanol producer BioFuel Energy Corp. jumped 62 percent after the Denver-based company announced it has settled some outstanding issues with its lenders. NEW YORK (AP) ¿ Shares of Vertex Pharmaceuticals Inc. fell after the company forecast a wider 2009 loss while raising $155 million through new debt and the sale of milestone payment rights for the hepatitis C drug candidate telaprevir.