Extensive sanctions in the last few years have resulted in price fluctuations in various markets. These fluctuations have caused a large part of the country's liquidity to move from productive activities to speculative activities and increase prices. Therefore, it is necessary to examine the conditions of different markets and adopt solutions to reduce speculation activities. Therefore, the purpose of this research is to answer these two questions: first, is there speculation in the four markets of foreign exchange, housing, gold, and cars? And secondly, can the speculation tax control the price fluctuations of these markets or not? For this purpose, the ARDL model was used in EViews software. The results of the research showed that the adjustment coefficient of the foreign exchange market is higher than other markets and speculators react faster to this market than other markets in unstable conditions. In addition, the expected price elasticity in all four markets has increased over time and has been more than one in the last few years. Therefore, speculation has not only existed but also increased in all four aforementioned markets in recent years. Also, the results showed that the product of the elasticity coefficient in the adjustment coefficient was more than one for the last few years, which indicates the effectiveness of adopting the speculation tax in these markets and can reduce the reaction speed of market traders to price changes. Therefore, it is recommended for policymakers to adopt a speculation tax in the short term to control the speculative activities in the aforementioned markets and direct liquidity from speculative activities to productive activities. Of course, the speculation tax can be a short-term emergency measure and not a long-term policy to suppress speculation. Because it leads to the withdrawal of liquidity from the intended markets.