Apple Computer upgraded at Citigroup: AAPL was upgraded from Hold to Buy, Citigroup said. Company experiencing several product transitions, but new products should drive second quarter growth. $80 price target. Alaska Communications upgraded at Merrill Lynch: Merrill Lynch said it was upgrading ALSK from Neutral to Buy on valuation and following the removal of private equity ownership overhang. Maintained $12.50 target. Citrix Systems upgraded at JP Morgan: JP Morgan said it is upgrading CTXS to Overweight based on channel strategy accelerating and multiple product cycles in 2006. Energizer Holdings upgraded at JP Morgan: JP Morgan said it is upgrading its rating on ENR to Neutral from Underweight. Views current valuation as reasonable. H&E Equipment Services initiated at Deutsche Bank: Deutsche Bank said it was initiating HEES with a Hold rating and a $27 target. H&E Equipment rated new Neutral at UBS: UBS said it is initiating coverage on HEES with a Neutral rating. Sets target price at $30. NOVA Chemicals downgraded at Merrill Lynch: Merrill Lynch said it is downgrading NCX to Sell based on weak demand for polyethylene. Lowered 2006 EPS estimates by 50 cents to $3.50. NRG Energy coverage initiated at Morgan Stanley: Morgan Stanley said it is initiating coverage on NRG with an Overweight rating and a $60 target price. Among the top of new high growth, power companies. Nucor upgraded at CIBC: NUE was upgraded from Underperform to Sector Perform, CIBC said. Company should be able to carry strong momentum through the second quarter. Pain Therapeutics downgraded at Citigroup: PTIE was downgraded from Hold to Sell, Citigroup said. Stock is already up 60% on the year, pricing in most of the benefits of the new oxycontin product. Superior Industries downgraded at Prudential: Prudential said it is downgrading SUP to an Underweight rating due to eroding outlook and assumed restructuring benefits pushed out. China and steel remain threats.