Piper Jaffray analyst Christopher Raymond keeps an Overweight rating on Alexion Pharmaceuticals (ALXN) with a $180 price target after this morning's announced acquisition of Achillion Pharmaceuticals (ACHN). The deal brings in danicopan, an oral Factor D inhibitor, as combination therapy with Soliris for the treatment of paroxysmal nocturnal hemoglobinuria and monotherapy for C3 glomerulopathy, and ACH-5228, a second generation oral Factor D inhibitor, expected to enter the clinic early next year, Raymond tells investors in a research note. The analyst likes the deal. Achillion has already shown proof of concept in PNH and strategically the company adds to the diversification of Alexion's pipeline, says Raymond. The analyst remains a buyer of Alexion shares.