Trading on the momentum of price movements may then become a rational activity that becomes self-fulfilling, as investors decide to “ride the bubble” while it lasts. The bubble is inflated further by the asymmetry between those who bet that prices will rise and buy, and those who forecast a fall, but stay out because to sell short is too costly.
在这样的情形下，价格可能和通过假设汇集所有市场信息的集体智慧所确定的基本面相去甚远。当投资者决定在泡沫破灭之前“驾驭泡沫”的时候，按照价格变化趋势进行交易就变成了自我实现的理性行为。由于那些赌价格会上涨并且买入的人和那些预测价格会下跌但是因为卖空代价太大而仍然坚持的人之间的不对称，泡沫进一步被吹大。