Suppose the desk just sold a batch of at-the-money (ATM) calls and is currently Delta neutral. The underlying stock suddenly drops 10%. To avoid breaching a strict intra-day Delta limit, should the trader buy or sell the underlying stock to rebalance?

假设交易桌刚刚卖出了一批平值看涨期权（ATM Call），且当前保持Delta中性。突然标的股票大跌10%，为了不突破严格的日内Delta限额，交易员现在应该买入还是卖出股票进行再平衡（Rebalancing）？