AstraZeneca's ( AZN) shares gained 2.1% after Bear Stearns upgraded the stock to outperform from peer perform, saying the company's worst-case scenario is already priced in and the stock is cheap. Shares were trading $1.17 higher to $56.25 Friday. The analyst sets a $64 price target on the stock. Negative trial data on AstraZeneca's proposed stroke drug NXY-059 triggered a selloff, says European pharmaceuticals analyst Alexandra Hauber, and the company's expected loss of its reflux drug Nexium and antipsychotic Seroquel in patent challenges at the end of the decade are already priced in. "Although further margin expansion seems increasingly hard to achieve ... we would not rule out the prospect that continuing outstanding execution could potentially provide further earnings surprises," Hauber wrote in a research report Friday. The company's sparse late-stage research pipeline got a boost yesterday when the company announced a collaboration with Bristol-Myers Squibb ( BMY) to help promote and develop two type 2 diabetes drugs, saxagliptin and dapagliflozin, the analyst noted.