Humana's Stock Plummets 3.57% on Record $450M Volume as It Ranks 280th in Daily Trading Activity

On October 10, 2025, Humana (HUM) reported a 3.57% decline in its stock price amid a 63.27% surge in trading volume to $0.45 billion. The healthcare insurer ranked 280th in terms of market activity for the day, indicating heightened investor scrutiny following recent developments in its strategic initiatives and regulatory landscape.

The stock’s sharp drop coincided with market reassessment of its position in the evolving healthcare sector. Analysts noted that the volume spike reflected a mix of institutional positioning and retail investor activity, though no direct correlation to earnings or earnings guidance was identified in the available data. The move contrasted with broader market trends, underscoring sector-specific volatility.

To run this back-test robustly I need to nail down several practical details. Please let me know (or confirm my default choices) for the items below, then I’ll proceed to code up the test: 1. Stock universe • Default I would use all U.S. common stocks listed on NYSE / NASDAQ / AMEX that have a valid price on each trading day. 2. Ranking time & trade price • Calculate the “top-500 by dollar trading volume” at each day’s close. • Enter all 500 positions at the next day’s open, exit them at that day’s close (1-day holding period). (If you prefer same-day close-to-close, or open-to-open, let me know.) 3. Weighting scheme • Equal-weight across the 500 names each day. 4. Transaction costs • Default assumption: 0.02% one-way (4 bp round-trip) to approximate commissions + slippage. • Let me know if you’d like a different figure or wish to ignore costs. 5. Portfolio aggregation • Daily portfolio return will be the simple average of the 500 individual stock returns (equal-weight). • Rebalance fully every day. 6. Analysis period • 2022-01-03 (first trading day of 2022) through 2025-10-10. If these defaults look good, just say “proceed” and I’ll run the back-test. If any item needs adjusting, please tell me and I’ll incorporate the change before proceeding.