The study investigates the business dynamics in selected Iranian industries during the period of 2003 to 2013. Business dynamics is regarded as an important indicator of the level of competitiveness in an industry. Business dynamics reflect both competition by new firm entries and also competition among incumbent firms. The study pays attention to the second type of business dynamics. Mobility indices are usually used to measure competition among incumbent firms in an industry. In the current study two proposed mobility indices (Mu and Mp) are computed. These indices are computed by transition matrix. The study also examined long run and short run perspective of business dynamics. The results of the study show that the mobility among the firms is low which means that there is low competition among these firms. The results also indicate the fact that mass construction, real-estate industry has been more mobile in the period of time in comparison to other industries.