Editor's Note: Green and red arrows refer to intraday stock price movement.NEW YORK ( TheStreet) -- CHANGE IN RATINGS Alexion Pharmaceuticals ( ALXN) numbers raised at Citigroup. Shares of ALXN now seen reaching $79. Estimates also increased, to match the company's new guidance. Buy rating. Alexion Pharmaceuticals ( ALXN) downgraded at Jefferies from Buy to Hold. Valuation call, based on a $69 price target. Digital Realty Trust ( DLR) initiated at Barclays with an Overweight rating and $72 price target. Data centers will benefit from strong secular demand growth in the coming years. F5 Networks ( FFIV) downgraded at Barclays to Equal Weight from Overweight. Checks suggest a blip in the rapid growth in server virtualization space in the near term. Price target raised to $95 from $90. Starwood Hotels ( HOT) rated new Buy at Jefferies. $64 price target. Company owns key assets in larger urban and luxury markets. Penn National ( PENN) numbers upped at Morgan Stanley. PENN estimates were boosted through 2011. Company is seeing better results in WV and PA. Overweight rating and new $38 price target. Penn National ( PENN) upgraded at Jefferies from Hold to Buy. $41 price target. Company is performing well and faces easier near-term comps. Polycom ( PLCM) estimates, target upped at UBS. PLCM estimates were boosted through 2011. Company is seeing better enterprise and government demand. Neutral rating and new $32 price target. Polycom ( PLCM) upgraded at Wells to Outperform. Estimates also boosted, given the company's strong earnings momentum. Riverbed Technology ( RVBD) target, estimates raised at Barclays. RVBD price target climbed to $50 from $38 on strong 3Q results with operating margins well ahead of estimates. 2010 and 2011 EPS estimates lifted to $1.15 and $1.50, respectively. Maintain Overweight rating. Riverbed Technology ( RVBD) upgraded at Jefferies from Hold to Buy. $60 price target. Company is becoming a clear market leader in WAN optimization. Riverbed Technology ( RVBD) upgraded at Canaccord from Hold to Buy. $60 price target. Company is realizing positive catalysts sooner than expected. Union Pacific ( UNP) price target raised at Credit Suisse to $110 from $107. Strong 3Q results, due to higher pricing, topped estimates. Maintain Outperform rating. Union Pacific ( UNP) upgraded at Wells to Outperform. Company continues to expand its margins, despite lower volumes. Union Pacific ( UNP) downgraded at Baird from Outperform to Neutral. $93 price target. Volume growth is decelerating and incremental margins could moderate. URS ( URS) rated new Buy at Keybanc. $50 price target. Stock is already pricing in fears of lower defense spending.