First, as plummeting stock prices caused the equity in investors’ accounts to fall below the maintenance margin, brokers began issuing margin calls, forcing investors to offload more assets to come up with the needed cash. When they failed to pay margin calls on time, their shares were sold by brokers, pushing stock prices down further.
一开始，这看上去只是自然修正。但保证金交易的普遍性导致下跌迅速演变为崩盘。首先，暴跌的股价导致投资者账户中的股票下降到维持保证金水平以下，于是经纪商开始催缴保证金，迫使投资者甩卖更多资产以获得所需要的现金。如果他们无法及时追加保证金，他们的股票就会被经纪商卖出，进一步打压股价。