MP Materials Shares Plummet 4.31% on $810M Volume Drop as Stock Falls to 131st Most Liquid in U.S. Market

MP Materials (MP) closed 4.31% lower on October 8, 2025, with a trading volume of $0.81 billion, marking a 29.48% decline from the previous day’s volume and ranking 131st among U.S. stocks by liquidity. The selloff followed a mix of market sentiment shifts and sector-specific dynamics impacting the rare earths producer.

Recent developments highlighted in the market included supply chain adjustments in critical minerals and evolving demand forecasts from downstream industries. Analysts noted that macroeconomic signals, including interest rate expectations, contributed to broader market volatility, with small-cap and resource stocks experiencing heightened sensitivity to cash flow concerns.

The backtesting framework for evaluating high-volume trading strategies remains constrained by current tool limitations. Existing platforms cannot dynamically rebalance portfolios of 500 stocks daily based on volume metrics. Alternative approaches include proxying the strategy through broad-based ETFs like SPY or utilizing external quantitative tools for full-scale implementation.

Backtesting this approach would require a multi-asset engine with access to comprehensive U.S. equity volume data, which is beyond the scope of this environment. Two workarounds are suggested: testing a 1-day holding period on a liquidity proxy ETF or exporting the strategy to platforms like Python/Zipline for full execution.