IDEXX Laboratories Stock Dives 1.44% as $230M Volume Lands at 482nd in Market Activity

On September 25, 2025, IDEXX Laboratories (IDXX) closed down 1.44% with a trading volume of $0.23 billion, ranking 482nd in market activity for the session. The stock's performance followed a mixed session across healthcare and diagnostics sectors amid broader market volatility.

Recent developments suggest heightened scrutiny of the veterinary diagnostics market, with analysts noting potential headwinds from regulatory reviews and competitive pricing pressures. While the company has historically benefited from its dominant position in companion animal health, recent investor sentiment appears cautious, reflecting broader macroeconomic uncertainties impacting discretionary healthcare spending.

Market participants are closely monitoring the company's upcoming earnings report for clarity on its Q3 guidance. Short-term technical indicators show declining momentum, with the stock failing to hold key support levels established in early September. Positioning data also reveals a reduction in open interest among institutional investors, signaling potential profit-taking after a recent consolidation phase.

To make sure I set up this back-test exactly the way you have in mind, could you please confirm a few details? 1. Universe: Which market should the "top 500 by trading volume" be pulled from (e.g., all U.S. listed common stocks, a specific exchange, or another universe)? 2. Entry / exit prices: Should we assume • Buy at today’s close and sell at tomorrow’s close, -or- • Buy at tomorrow’s open and sell at tomorrow’s close? (Both are common one-day‐hold conventions.) 3. Rebalance frequency: Confirm that the basket is re-selected every trading day. 4. Portfolio construction: Equal-weight each of the 500 names, correct? 5. Frictional costs: Any transaction cost or slippage assumptions to include? Once I have these points, I can determine whether the data universe and daily rebalancing can be synthesized with the available toolkit or if we should consider a practical approximation (e.g., a representative ETF or a smaller subset of stocks).