Mehdi Maranjory - Department of Accounting, chalous Branch, Islamic Azad University, chalous, Iran.

Surviving in highly competitive industries and attaining sustainable market growth require firms to continuously invest in R&D projects in order to innovate in products and technology. Literature shows that R&D investment can be significantly influenced by uncertainties in a firm’s external and internal environments. The purpose of this study is determining the role of product market competition on relation between environmental uncertainty and R&D Investment. The present research is of practical type in terms of purpose and has descriptive- correlational nature. The statistic population includes all active firms in Tehran securities market between ۲۰۱۳ to ۲۰۱۹. By using systematic removal method, ۱۲۲ firms were chosen as sample. In order to investigate the relation between research variables, multivariate regression has been used. The results indicated that there is a negative and significant relation between environmental uncertainty and R&D Investment in Tehran securities market. Also, the product market competition negative relation between environmental uncertainty and R&D Investment will strengthen it.

Product Market Competition, environmental uncertainty, R&D Investment