[] a situation or period of time when the prices of shares, currencies, etc. keep going up and down very quickly and by a large amount （股票、货币等的价格的）大起大落◆the stock market roller coaster 大起大落的股市◆The company has had a roller-coaster year on the stock market (= the price of its shares has kept moving up and down). 这一年这家公司的股票价格大起大落。