The stock market experienced a notable downturn today, with the S&P 500 index declining by 2.64%. Over the past five days, the index has seen a decrease of 2.59%, although it has managed to gain 1.72% over the last 30 days. In terms of market capitalization, the performance varied significantly among large, mid, and small-cap stocks. The Allstate Corp. emerged as the top performer in the large-cap category, achieving a return of 4.82%. Conversely, Marvell Technology, Inc. faced the steepest decline, with a return of -16.74%. Mid-cap stocks also showed mixed results, with The Clorox Co. leading at 5.03%, while Teradyne, Inc. fell by 12.03%. In the small-cap sector, The Cooper Cos., Inc. excelled with an 8.58% return, while Planet Labs PBC struggled, posting a significant loss of 25.98%. Overall, the advance-decline ratio across the market indicated that 1,266 stocks advanced compared to 2,854 that declined, reflecting a challenging day for investors.