1) The stock market prices plummeted

股市价格猛跌
2) Prices started a downward plunge.

价格开始猛跌。
4) The price fall suddenly(go down with a run;slump;decline heavily)

物价猛跌
5) The stocks slumped.

股票价格狂跌。
补充资料:股市
参见:股票市场