William Blair analyst Raju Prasad reiterated an Outperform rating on Alexion Pharmaceuticals after the company provided its fourth quarter operating results. Prasad said that while the company's 2020 guidance was below consensus, it is likely conservative, as the company has historically provided conservative guidance and last year the company beat and raised guidance every quarter. The analyst said he believes Alexion's complement franchise sales will continue to grow in neurology, and that he continues to believe Alexion will be "active" on the business development front in 2020.