OXY's 7.31% Plunge on $1.97 Billion Surge in Trading Volume, Ranked 39th in Market Activity

On October 2, 2025, Occidental Corporation (OXY) closed with a 7.31% decline, marking its lowest price in recent months. The stock saw a surge in trading activity, with a volume of $1.97 billion—323.09% higher than the previous day—which ranked it 39th in market activity. The sharp drop contrasted with broader market trends, highlighting investor caution ahead of potential sector-specific developments.

Recent market dynamics suggest heightened sensitivity to energy sector fundamentals. Analysts note that OXY’s performance may reflect shifting expectations around oil price trajectories, with traders recalibrating positions amid evolving geopolitical and supply-demand narratives. While no company-specific announcements directly triggered the move, the stock’s volatility underscores its exposure to macroeconomic signals.

To run this back-test accurately I need to pin down a few practical details that the data-pull and calculation steps depend on: Trading universe—Should we consider all U.S. common shares (NYSE, NASDAQ & AMEX) or a narrower list (e.g. Russell 3000, S&P 500, etc.)? Weighting scheme inside the 500-stock basket (equal-weight each day, or volume-weighted, or …)? Execution price assumptions—Buy at today’s close and exit at tomorrow’s close (close → close)? Or buy at tomorrow’s open and exit at tomorrow’s close (close → next open, or open → close)? Transaction costs / slippage—Ignore them, or include a per-trade cost? Once these are settled I can lay out the exact data-retrieval plan and run the automated back-test.