SPGI Plunges 6.67% on Surge in Trading Activity Volume Hits $1.66 Billion 53rd-Highest in Market

On September 18, 2025, , marking its largest intraday drop in recent months. The stock saw a surge in trading activity, . The sharp sell-off was driven by a combination of sector-specific pressures and broader macroeconomic concerns, though no direct company-specific catalysts were cited in available reports.

The move followed a broader market selloff in equity indices, with investors rotating into defensive assets amid rising . While S’s fundamentals remain unchanged, the stock’s volatility highlighted its sensitivity to macroeconomic repositioning. Analysts noted that the decline could reflect profit-taking after a prolonged rally rather than a fundamental shift in the company’s trajectory. However, the magnitude of the drop raised questions about short-term liquidity dynamics in the sector.

Backtesting parameters for a daily-rebalanced strategy involving S would require clarification on several operational details. Key considerations include the universe (e.g., S&P 500 constituents vs. all U.S.-listed stocks), entry/exit timing (close-to-close vs. close-to-open-to-close), position sizing (equal-weight vs. volume-weighted), and cost assumptions (commissions, slippage). Once these parameters are finalized, a backtest covering January 1, 2022, to September 18, 2025, could be executed to assess the strategy’s historical performance.