BIIB got oversold due to the unsatisfactory results of their Alzheimer studies . This catalyst gives investors opportunity to buy the equity at a discount from it usual value. In addition, BIIB beats their Q1 2019 earnings ( $6.98 EPS vs expectation of $6.87) and the market does not react positively, creating furthemrore a buying opportunity. If we compare the financial ratios of the peers in the same sector , BIIB is clearly at discount of the sectors average and has a strong upside.