Dexcom Clings to Gains as Volume Plummets to 473rd in U.S. Rankings

Dexcom (DXCM) closed higher by 0.44% on October 9, 2025, despite a 42.79% drop in daily trading volume to $230 million, ranking it 473rd among U.S. equities. The stock's performance came amid mixed market sentiment, with investors balancing short-term volume declines against broader sector dynamics in medical technology.

Analysts noted that the company's recent regulatory filings highlighted ongoing supply chain adjustments, which could influence investor confidence in the near term. While no specific earnings or partnership announcements were reported, the stock's volume contraction suggested reduced immediate trading interest compared to recent sessions.

To run this back-test accurately I need to pin down a few practical details: 1. Market universe • Should we consider all U.S. common stocks (NYSE + NASDAQ + AMEX) or a different universe? 2. Rebalancing logic • Do we “rank by today’s volume at the close, buy at that close, then exit at tomorrow’s close” (close-to-close return)? • Or do we “rank by yesterday’s volume at the close, buy at today’s open, exit at today’s close” (open-to-close return)? • If neither of these matches what you have in mind, please specify. 3. Weighting scheme • Equal-weight across the 500 names each day (typical for this type of study), or another weighting? 4. Transaction-cost assumptions (commissions/slippage) • Apply a flat transaction cost per trade (e.g., 5 bps each side), or ignore costs? Once I have these points confirmed I can configure the back-test engine and show you the performance report.