Biogen BIIB, -2.48% shares fell 2.6% after an analyst scoffed at the possibility of a Food and Drug Administration approval for the company’s experimental Alzheimer’s disease treatment. “There are so many reasons we think aducanumab is getting rejected, our word count restrictions don’t allow us to put them all here,” Baird analyst Brian Skorney wrote in a Dec. 2 note. Skorney’s primary argument is that he believes data from the most recent clinical trial doesn’t make for a compelling case to take to the FDA. Earlier this year, Biogen’s stock tumbled to a three-year low after the company said it would stop trials for the therapy, prompting Mizuho analyst Salim Syed to say “aducanumab is dead, and we’d argue so is the beta-amyloid hypothesis.” But then in October Biogen announced plans to pursue FDA approval following discussions with the regulator. The biopharmaceutical company has said it will release additional clinical trial information about aducanumab on Dec. 5. Separately, shares of Cortexyme Inc. CRTX, +16.04%, which is also developing an Alzheimer’s treatment, jumped in morning trading, by 20%. Shares of Biogen have fallen about 3% year-to-date, compared to the S&P 500 SPX, -0.69%, which has gained about 24%.