بررسی وضعیت ریسک سیستماتیک β ) ) شرکت‌های پذیرفته شده در بورس اوراق بهادار تهران (1374-1378)

From a certain point of view, risks are divided into two categories: systematic (i.e. market type) and unsystematic (i.e. non-market type). This categorization is majorly applied on financial papers and it has been used in this study. The risks a company encounters for getting more output, on the hand depend on the conditions of society and market (generally the political developments, economic situations, chaos and war, economic periods, etc). On the other hand, they depend on internal situations of the company such as company management, product prices, marketing issues, legal matters, capital status, and so on. The risks related to the whole activities are called systematic risks and those related to a certain company or activity are categorized as unsystematic. The latter could be eliminated by means of adding variety to investment activities. In other words, if the stock status of a company alters with the change of macroeconomic factors, the company faces a high systematic risk and the other way round. The amount to which the different companies is affected by the market risk factors (i.e. macroeconomic factors) is not the same. Based on this categorization, this study calculates systematic (market) risks in Tehran Stock Exchange. It proposes five hypotheses and tests them according to theoretical finance literature. In the end, it offers some recommendations for investors, capital market officials and researchers.