Friday’s biggest gaining and declining stocks By: MarketWatch October 21, 2011 at 10:10 AM EDT Among the biggest advancers: Altera, Harman, Seagate and LyondellBasell, and the biggest decliners included Acme Packet. Read More >> Related Stocks: Altera Corp Chipotle Mexican Grill Harman International LyondellBasell Industries SanDisk Corp Seagate Technology Plc Synaptics Inc