Biogen’s Trading Volume Surges to $420M Ranking 341st as Rare Disease Sales and Institutional Buys Drive 1.07% Gains

Biogen Inc. (NASDAQ:BIIB) closed July 31, 2025, with a 1.07% gain, marking a significant outperformance in a mixed market. The stock saw a 74.62% surge in trading volume to $420 million, ranking it 341st in daily activity. This momentum followed key developments in its business strategy and market position.

The biotech firm raised its full-year profit forecast amid strong demand for rare disease treatments, including Skyclarys, Spinraza, and Qalsody. Second-quarter sales from its rare disease portfolio reached $543 million, reflecting resilience despite declining revenue from older multiple sclerosis therapies. Leqembi, Biogen’s Alzheimer’s drug developed with Eisai, also contributed to the upward trajectory, with U.S. sales exceeding $63 million in Q2—a fourfold annual increase. Improved diagnostic accessibility for Alzheimer’s, including FDA approval of a blood test in May, has gradually boosted patient adoption of the high-cost therapy.

Institutional activity further supported investor confidence. Recent transactions included purchases by Renaissance Technologies LLC and Carmignac Gestion, while HSBC initiated coverage with a “buy” recommendation. Biogen’s leadership changes, including the appointment of Dr. Jane Grogan as head of research, signaled strategic realignment. Meanwhile, institutional ownership remains robust, with 89% of shares held by professional investors.

The strategy of purchasing the top 500 stocks by daily trading volume and holding them for one day delivered a 166.71% return from 2022 to July 30, 2025. This approach outperformed the benchmark return of 29.18%, generating an excess return of 137.53%. The strategy’s success is attributed to its ability to capture market momentum effectively while managing risk, as evidenced by the consistent high returns despite varying market conditions.