NEW YORK ( TheStreet) -- CHANGE IN RATINGSApache ( APA) downgraded at Morgan Stanley from Overweight to Equal-weight. Sector will be hurt by lower natural gas prices. Atheros Communications ( ATHR) downgraded at Barclays to Equal Weight from Overweight on valuation. 2010 and 2011 EPS estimates set at $2.20 and $2.40, respectively. Maintain $40 price target. CF Industries ( CF) downgraded at UBS from Neutral to Sell. $81 price target. Investors would have been better served with the AGU deal. Chesapeake Energy ( CHK) downgraded at Morgan Stanley from Overweight to Equal-weight. Valuation call. Diamond Foods ( DMND) reinstated at BofA/Merrill 8:15 AM EDT DMND coverage reinstated with a Neutral rating and $45 price target. Recent acquisition of Kettle Foods was a bullish move. Entropic Communications ( ENTR) upgraded at Barclays to Overweight from Equal Weight as the company should benefit from broadening customer base. Price target jumped to $7 from $4.50. 2010 and 2011 EPS estimates set at 30 cents and 54 cents, respectively. Hasbro ( HAS) downgraded at Needham from Strong Buy to Buy. Valuation call, based on a $45 price target. Ironwood Pharmaceuticals ( IRWD) initiated at BofA/Merrill with a Buy rating and $17 price target. KLA-Tencor ( KLAC) downgraded at Oppenheimer from Perform to Underperform. See a sequential decline in Semi cap equipment orders in the second quarter. Legg Mason ( LM) upgraded at FBR from Underperform to Market Perform. Outflows appear to be stabilizing. $33 price target. Lam Research ( LRCX) downgraded at Oppenheimer from Outperform to Perform. Semi-cap equipment orders are likely to fall 15%-20% sequentially in the second quarter. Patterson-UTI ( PTEN) downgraded at Morgan Stanley to Equal-weight. $20 price target. Lower natural gas prices are weighing on North American drilling demand. Sirona Dental ( SIRO) upgraded at Suntrust from Neutral to Buy. $50 price target. Company is positioned well to exceed consensus analyst estimates. Ulta Salon ( ULTA) downgraded at Jefferies from Buy to Hold. Valuation call, based on a $25 price target. Company facing more difficult comparisons. Wal-Mart ( WMT) upgraded at Citi to Buy from Hold on expectations of more aggressive pricing. Price target jumped to $65 from $54. 2011 and 2012 EPS estimates set at $4.04 and $4.49, respectively.