On the Possibility of Price Decreasing Bubbles
论证理性泡沫不一定推高股价：泡沫推高利率会压低基本面价值，导致泡沫加基本面之和反而低于无泡沫时的价格，从而出现价格下跌泡沫，资产可能被低估。
It is often argued that a rational bubble, because it is positive, must increase the price of a stock. This argument is not valid in general: as soon as bubbles affect interest rates, the fundamental value of a stock depends on whether or not a bubble is present. The existence of a rational bubble then might, by raising equilibrium interest rates, depress the fundamental to such an extent that the sum of the positive bubble and decreased fundamental falls short of the fundamental, no-bubble price. Under conditions made precise below, there can therefore be price decreasing bubbles, and an asset can be undervalued.