The stock market is influenced by other parallel markets and macroeconomic variables; such variables have impacts on the behavior of financial market players. Accordingly, this study first examines the existence of herding behavior among investors in the Tehran Stock Exchange (TSE). It then investigates the effects of exogenous economic variables on this industry-level behavior in the Tehran Stock Exchange (TSE) throughout 2008- 2018. For this purpose, 12 different industries were studied, and the results of nonlinear regression analysis showed the existence of herding behavior in all selected industries in the bearish market. However, this is not true for the bullish market. The findings also indicate that the effects of exogenous variables are not the same in different industries.