McKesson Plunges 2.72% Amid 71.87% Volume Surge, Climbs to 129th in Trading Activity

On October 3, 2025, McKesson (MCK) closed with a 2.72% decline, marking its third consecutive session of negative performance. The stock traded with a volume of 0.87 billion shares, a 71.87% increase from the prior day, ranking 129th among active stocks. The heightened trading activity suggests potential shifts in institutional positioning or sector rotation dynamics within the healthcare distribution space.

Analysts noted mixed sentiment in pre-market commentary, with some observers attributing the decline to broader market rotation out of healthcare stocks. A key factor identified was the recent earnings report from a major competitor in the pharmaceutical distribution sector, which triggered comparative valuation pressures. While McKesson's fundamentals remain stable, the stock's sensitivity to macroeconomic indicators such as interest rate expectations and healthcare policy developments continues to influence short-term volatility.

Technical indicators show the stock has remained within a defined trading range for the past six weeks, with resistance at $225 and support near $218. The recent volume surge suggests potential breakout attempts, though sustained momentum has yet to materialize. Positioning data from the last two weeks indicates reduced open interest among speculative traders, signaling caution in the options market.

To set up an objective, reproducible back-test I need to pin down a few practical details: 1. Market universe • Do you want all U.S.–listed common stocks (NYSE + NASDAQ), or a different universe? • Are ETFs/ADRs/penny stocks to be excluded? 2. Rebalancing rule • “Top 500 by daily trading volume” – should the ranking be done on yesterday’s volume and the trade executed at today’s open, or ranked at today’s close and traded at the next open? • Equal-weighted basket each day? 3. Trade execution price • Buy at the day’s open and sell at the next day’s close (1-day holding period), or open-to-open, or close-to-close? 4. Frictional costs • Assume zero transaction cost/slippage, or apply a commission (e.g., 2 bps in/out)? 5. Benchmark / output • Any benchmark you’d like reported (e.g., SPY or equal-weight universe)? • Key statistics beyond CAGR and max drawdown (e.g., Sharpe, win rate)? Once these are set I can pull the requisite data and run the back-test from 2022-01-03 to the present.