William Blair analyst Raju Prasad earlier today initiated coverage of Alexion Pharmaceuticals with an Outperform rating and $146 fair value estimate. The shares have been weak because of Alexion's intellectual property issues in the United States and Europe and the threat from competitive products to the durability of its complement franchise, Prasad tells investors in a research note. The analyst, however, believes Alexion will remain the leader in atypical hemolytic uremic syndrome and paroxysmal nocturnal hemoglobinuria with its Ultomiris transition. This should be supplemented by the continued launch and potential market expansion in generalized myesthenia gravis and the neuromyelitis optica spectrum disorder launch beginning in the United States in the second half of 2019, says Prasad. He sees current valuation levels as a positive risk/reward setup.