Adtran ( ADTN) upgraded at Merrill from Sell to Neutral. Buybacks should support the stock in the near term, and business is poised to recover some time in 2008. Ametek ( AME) downgraded at Friedman, Billings Ramsey from Outperform to Market Perform. Valuation call, based on a $46 price target. Fundamental outlook remains strong. Amedisys ( AMED) downgraded at Deutsche Bank from Buy to Hold. Valuation call, as the stock is nearing the $44 price target. Short squeeze may also be over. BladeLogic ( BLOG) initiated at UBS with Neutral rating. Price target set at $31 and FY 2008 eps estimates begin at $0.07. Dynamic Material ( BOOM) downgraded at Jefferies to Hold rating from Buy. FY 2008 eps estimates hold at $2.35 while price target lifts to $58 from $45. Cognos ( COGN) downgraded at Robert Baird from Outperform to Neutral. Valuation call, as the stock has rallied following the BOBJ takeover. $50 price target. Digital River ( DRIV) downgraded at Oppenheimer from Buy to Neutral. New analyst set a $50 price target, as SYMC is pressuring market pricing. General Maritime ( GMR) downgraded at Bear Stearns from Outperform to Peer Perform. Company will likely continue to realize lower tanker rates headed into the fourth quarter. The stock offers an 8% dividend yield, but lacks significant catalysts.