Stifel analyst Paul Matteis maintained a Hold rating on Biogen and lowered his price target on shares to $233 from $346 following the drop in the company's stock due to its announcement it would stop its aducanumab phase III studies, ENGAGE and EMERGE, for futility. The analyst said to take a "wait-and-see approach" until there is more visibility in the company's growth and its contingency plan. Matteis noted there are two major catalysts in 2019 -- Novartis Type-2 SMA gene therapy data at AAN, BIIB092 PSP data in the second half of 2019 -- but added that it is hard to get constructive ahead of either event as he worries about the first and lacks conviction in the second.