Once a fund manager suffered a setback in their US stock SPX position, losing a total of 20 million USD in a single blow. What does this tell us? The heavy cost of excessive leverage and poor position management. In any market, don’t think about going all-in; no matter how good the liquidity on the exchange, an extreme market fluctuation can wipe you out. Instead of blindly chasing highs, it’s better to prioritize risk control—proper position sizing and stop-loss settings are the true secrets to long-term survival.