NEW YORK ( TheStreet) -- CHANGE IN RATINGSChesapeake Energy ( CHK) rated new Buy at Wunderlich. Valuation call, based on a $22 price target. Continental Resources ( CLR) rated new Hold at Wunderlich. Valuation call, based on a $72 price target. F5 Networks ( FFIV) rated new Buy at Needham. $130 price target. Stock is attractive, following a 30% selloff. Juniper Networks ( JNPR) downgraded at Needham from Buy to Hold, Needham said. Routing and enterprise switching markets are facing fundamental changes. Medtronic ( MDT) upgraded at Credit Suisse from Neutral to Outperform, Credit Suisse said. $44 price target. Emerging market should drive sales growth and the company deserves a higher multiple. Pharmacyclics ( PCYC) rated new Buy at Brean Murray. $80 price target. Lead drug continues to perform well in clinical trials. PulteGroup ( PHM) upgraded at FBR from Market Perform to Outperform, FBR Capital Markets said. $11 price target. Industry fundamentals remain strong and the company has solid operating leverage. Sina Corporation ( SINA) upgraded at Oppenheimer to Outperform from Perform, Oppenheimer said. $70 price target. Attractive valuation. Tempur-Pedic ( TPX) downgraded at Piper from Overweight to Neutral, Piper Jaffray said. $22 price target. Company could continue to struggle to grow over the next several quarters. Tempur-Pedic downgraded at William Blair from Outperform to Market Perform, William Blair said. Competitive pressures have intensified.
STOCK COMMENTS / EPS CHANGES
Apache ( APA) numbers cut at UBS. Shares of APA now seen reaching $127, UBS said. Estimates also lowered on the back of lower production growth assumptions. Buy rating. Halliburton ( HAL) estimates, target cut at Guggenheim. Shares of HAL now seen reaching $33, according to Guggenheim. Estimates also reduced, given the company's new guidance. Neutral rating. Halliburton estimates lowered at UBS through 2013, UBS said. Lower NA 2Q guidance on guar costs. Buy rating and $45 price target. Coca-Cola ( KO) estimates lowered at JP Morgan through 2013, JP Morgan said. Company is seeing slower growth in Europe. Neutral rating and $76 price target. LyondellBasell ( LYB) numbers lowered at Jefferies. Shares of LYB now seen reaching $52, Jefferies said. Estimates also lowered on potential summer destock. Buy rating.