Shares of Cassava Sciences Inc. /zigman2/quotes/204212356/composite SAVA +0.88% jumped 24% on positive data from a mid-stage trial for its experimental Alzheimer's disease drug, PTI-125. The data, which found that the therapy reduced cerebrospinal fluid and plasma biomarkers for Alzheimer's, was released Dec. 5 at the Clinical Trials on Alzheimer's Disease meeting in San Diego. Biogen /zigman2/quotes/201531540/composite BIIB +0.47% also released somewhat controversial data about its late-stage Alzheimer's candidate at the conference on Thursday. Cassava stock is up 163% year-to-date. The S&P 500 /zigman2/quotes/210599714/realtime SPX +0.83% is up 25%.