The most plausible explanation, however, is that traders were gaming the system. The Hong Kong exchange is not alone in running a 10-minute auction every afternoon to settle outstanding trades: almost every other major market does this too, to calculate a price that will satisfy as many orders as possible. But unlike others, Hong Kong has no system of random closing: the auction ends every day at 4:08. That means that market participants have an incentive to time their bids. In this case, the downswing in HSBC caused by an order seconds before the deadline knocked about 212 points off the HSI. An issuer of index options callable that day might have been willing to wear a big loss on the shares.
不過，最有可能的解釋，是交易員在利用系統進行賭博。香港證交所每天下午進行10分鐘的收市競價交易，以結清尚未交易的買賣盤。香港證交所并非唯一采取這種機制的證交所，幾乎每一個主要市場都有這種機制，即計算出一個價格，以滿足盡可能多的買賣指令。但與其它交易所不同的是，香港沒有隨機收市的機制：競價交易在每日16:08時結束。這意味著，市場參與者有擇時提交競價的動機。此次，在截止期限之前幾秒鐘提交的一個賣出指令，導致匯豐股價暴跌，使恒生指數瞬間跌落212點。可在當天行使的指數買入期權的發行者，也許愿意承擔股價大跌的損失。