Developing countries such as Iran are subject to instability in macroeconomic variables such as exchange rates and stock prices. These variables are changing more in developing countries than in advanced economies, and these fluctuations create an uncertain environment for investors. Changes in exchange rates can have different effects on stock prices; the food products group on the stock exchange operates in the field of production and supply of food products, and is usually in the capital market. These companies meet their financial needs by financing through the capital market. The purpose of this study is to compare the symmetry of the effect of exchange rate growth on the growth of the food industry stock index and the growth of the overall index. For this purpose, the required information and data were collected in the form of a time series and daily, from the beginning of March 2019 to March 2023. The autoregression method with nonlinear explanatory lags was used to estimate the model. The results obtained from the estimation of the food industry index model show that the growth of the dollar has an asymmetric effect on the growth of the food industry index; however, the results of the estimation of the total stock exchange index model showed that the growth of the dollar has a symmetric effect on the growth of the total stock exchange index. Considering that the food industry stock market is a part of the stock exchange and, in addition, the heterogeneity in the food industry sector is greater than that of the total stock exchange, it is possible to consider the size and diversity of the product as important factors in the asymmetry of the effects of currency on financial markets.