There was another nasty twist: Many accumulators required investors to double down on purchases if shares dropped, buying 2,000 shares instead of 1,000 at a price that now put them in the red.

• 还有另一个讨厌之处：很多累股合约都要求投资者在股价下跌时双倍买进，也就是说，如果股价下跌，投资者要买进2,000股而不是1,000股，尽管合同规定的价位已使所进行股票投资亏本。