Financial markets are considered as a particular important capital market instruments an allocation of financial resources mobilization process. Considering the importance of strategic financial and economic market, when the disruption and diversion occur widely in it, mobilization and allocation of financial resources of the countries are faced with serious problems. One of the factors regenerator these issues is price bubble. Generally, when the price of a share is different from its future expected price, market bubble term is introduced. This paper explores validity of present value model with time – varying expectations, by use of newly developed Momentum Threshold Cointegration test, M-TAR, to investigate if there is any asymmetric adjustment in long-run prices and dividends in Tehran stock Exchange during 2000:M3 to 2008: M10? Empirical results indicate that long-run prices and dividends cointegration relationship doesn't hold for Tehran's stock exchange, which attests to the presence of rational bubbles.