Regeneron Shares Plummet 2.42% Amid Delayed Alzheimer’s Trial and Biotech Sector Turbulence 630M Volume Ranks 191st on October 6 2025

On October 6, 2025, Regeneron Pharmaceuticals (REGN) closed down 2.42% with a trading volume of $0.63 billion, ranking 191st in market activity for the day. The stock's performance was influenced by a combination of strategic updates and broader sector dynamics. Recent developments highlighted include the company's decision to delay a key Phase III trial for its experimental Alzheimer’s drug, which introduced uncertainty around regulatory timelines. Additionally, analysts noted increased market sensitivity to biotech sector volatility following a recent FDA guidance shift on monoclonal antibody approvals.

Market participants observed that the decline occurred despite Regeneron maintaining its 2025 revenue guidance. However, the stock underperformed relative to peers as investors reassessed risk profiles in light of recent clinical trial setbacks across the industry. Short-term technical indicators showed bearish momentum, with the stock breaking below key support levels established over the previous quarter. Trading volume, while above average for the biotech sector, failed to confirm a strong directional bias.

To run this test rigorously I’ll need to pin down a few practical details and confirm that the design matches what you have in mind: 1. Stock universe • Should we rank all U.S.-listed common stocks each day, or restrict the list (e.g., only S&P 500 constituents, only NASDAQ/NYSE, etc.)? • If the intention is “all U.S. stocks,” be aware that the daily top-500 list will change continuously and may include thousands of tickers over the sample period. 2. Trade price & execution assumptions • Open today, close tomorrow? (Most volume-factor studies buy at today’s close and exit at tomorrow’s close; but you might prefer next-day open for realism.) • Any transaction-cost or slippage assumption? 3. Weighting scheme • Equal weight (default)? • Value-weight by market value or dollar-neutral weighting? 4. Tool capability note Our current back-test engine handles single-ticker or fixed basket strategies out of the box; building a dynamic 500-stock basket per day will require a custom data-prep step. That’s fine—we can script it—but we need clarity on the above items before we start pulling data. Once I have your confirmation (or preferred defaults), I’ll generate the data-retrieval plan and run the back-test.