Alexion has had its share of controversies. Concerns over the company’s sales practices have dogged the rare-disease biotech and led to major C-suite shake-ups. But the firm has attempted to rebuild trust among patients and investors, and has acquired or partnered with upstart biotechs such as Syntimmune and Caelum Biosciences. Though these deals are filled with early-stage and unproven assets, many investors still see upside.

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