Redeye explains the spike in BioArctic's share price with the very positive view of the FDA experts on a related drug candidate, aducanumab, also developed by Biogen/Eisai. FDA states in advance of the November 6 meeting that there is a "substantial evidence of the effectiveness" of aducanumab, and increases its chances of approval. The view will have a large impact on the way the market views BioArctic's BAN2401 and, as a result, on the stock price.