M.A. Thesis:

Firm size٫ corporate debt٫ R&D activity٫ and agency costs

The main purpose of this study is to determine the relationship between company size, debt, research and development activities and agency costs in companies listed on the Tehran Stock Exchange. Research and development activities are the main and main sources of knowledge and technology developments. Most countries expand research and development activities to continue their economic growth. This research was conducted for a period of 5 years between2014 and 2018. Sample information The studied companies were collected after reviewing the availability of their information and classified with the help of Excel software and analyzed with the help of Eviews software. In this research, the company's size variables, debts, Research and development activities were considered as independent variables and agency costs as dependent variables and short term debts and previous agency costs as control variables. The results of the research of the first hypothesis indicate the existence of a significant and negative relationship between the size of the company and agency costs and in the second hypothesis of the research that at the level of 95% which shows the effect of a significant and positive relationship between debts and agency costs and The third hypothesis of the research is the existence of a significant 95% relationship between research activities and agency costs.

Keywords: Firm size, corporate debt, R&D activity, and agency costs