The stock was down 2.53% to $224.38.
Revenue for the first quarter of 2019 rose 11% from a year earlier to $3.49 billion, beating Wall Street's estimates of $3.4 billion. Adjusted earnings per share were $6.98, in line with analysts estimates. The revenue result was an 11% year-over-year increase.
"Biogen delivered strong financial results in the first quarter driven by the solid operational performance of our MS, SMA, and biosimilars franchises," said Michel Vounatsos, Biogen's CEO. "However, we are deeply disappointed with the discontinuation of aducanumab for Alzheimer's disease. We followed the science, and unfortunately the outcome was not as we had hoped. We continue to believe we can create value for patients and investors by capitalizing on opportunities in neuroscience, and we remain focused on allocating capital to the areas we believe have the highest potential return for shareholders."
Biogen's Tecfidera drug for multiple sclerosis brought in $999 million of revenue, an increase from sales a year earlier of $987 million. Revenue for Spinraza, a treatment for spinal muscular atrophy, was $518 million.
The stock has declined nearly 24% so far in 2019.