M.A. Thesis:

Relationship earnings quality and quality audit with the Cost of equality considering the size of the company

This research attempts to test the relationship between quality of profit and audit quality with the cost of common stock of listed companies in Tehran Stock Exchange considering the role of moderating the size of the company. The statistical population of the companies listed in the stock market is from 2009 to 2016. These samples included 142 companies. A comparison of the relation between the quality of profit and the cost of common stock shares shows that in large companies compared to small firms earnings quality has a stronger relationship with the cost of common stock. It can be deduced therefore the larger the company becomes larger with the increase in the quality of profit the cost of corporate common stock will decrease more. Also the results of the research show that size of a company larger the relationship is higher between the quality of the audit and the firm's common stock costs.

Keywords: Key words: Earning quality ،Audit quality ، Common stock cost ،Cost of Capital