The SPY index has experienced significant fluctuations over the past week. After attempting to hold at 540 on September 6, it saw a selloff on September 8, with potential declines to 537 and 533. By September 9, the index approached 548, reaching 547.30 but faced resistance at 546.41. On September 11, SPY broke below the 545 level and quickly fell to the 542-543 area. The SPX 5400 level remains a key point for potential options-derived support. Investors are also watching last Friday's lows for further movements.