LyondellBasell (LYB) Plummets 4.78% in Largest Single-Day Drop Since [Date], Trading Volume Ranks 330th in U.S.

On September 15, 2025, , marking its largest single-day drop since [date]. , ranking 330th in trading activity among U.S. equities. The move came amid market reassessment of energy transition dynamics and feedstock cost volatility, though no direct corporate announcements impacted the session.

Analysts noted that the selloff aligned with broader sector rotation rather than company-specific developments. Recent earnings releases and capital expenditure plans had already been priced into the stock, leaving macroeconomic factors as the primary driver. The decline followed mixed signals from global petrochemical demand forecasts, with Asian markets showing reduced near-term growth expectations.

To execute a back-test for LYB's performance, several parameters require clarification: market scope (entire U.S. universe or Russell 3000/S&P 1500), execution timing (open vs. close pricing), price adjustment conventions, and transaction cost assumptions. Rebalancing strategies also need definition, including whether to equally weight 500 securities daily or apply price filters to exclude low-capitalization stocks. Once these details are confirmed, , 2022, to the current date, incorporating daily volume rankings and trade signals.