Change in RatingsAmylin ( AMLN) upgraded at Citigroup from Sell to Hold. $17 price target. Valuation call, as the company needs to see FDA approval of its LAR and the rejection of Novo's Iria for the stock to move higher. Atmos Energy ( ATO) upgraded at Merrill to Neutral. $30 price target. Estimates also raised to reflect the company's increased regulatory outlook. Avery Dennison ( AVY) downgraded at Credit Suisse to Neutral from Outperform based on weak end-market demand, FX headwinds and valuation. Lowered target price to $46 from $54. Career Education ( CECO)upgraded at Morgan Stanley from Underweight to Equal-weight. $17 price target. Stock is down 22% over the past month, and pricing in poor fundamentals. Dollar Tree ( DLTR) upgraded at JP Morgan from Neutral to Overweight. Company has strong sales momentum and a good balance sheet. Estimates also raised, aided by the repurchase program. Jabil Circuit ( JBL) upgraded at Credit Suisse to Outperform from Neutral based on valuation and low expectations. Lowered target price to $10.50 from $17. Coca-Cola ( KO) downgraded at Deutsche from Buy to Hold. $56 price target. Company will face lower volumes across the board and negative currency effects in the coming quarters. Monsanto ( MON) upgraded at JP Morgan from Neutral to Overweight. Fertilizer problems have been overblown, and estimates were raised through 2008 because of higher expected Roundup profits. Piedmont Natural Gas ( PNY) downgraded at Merrill to Underperform. $29 price target. Valuation call, with the stock trading at a 44% premium to its peers.