Abstract

Quality auditor and auditors of larger firms have a positive effect on profit is unusual. The auditors smaller negative effect on profit companies profit is unusual. Change to larger audit shows the quality of earnings and to respond more investors positive changes in income and increased costs and reduced profitability is less negative price changes. Similarly, switching to a smaller auditor confirms the low quality of earnings, resulting in a negative response to the market. In this article market reaction (response investors) the quality of the audit and the auditor were studied in the Tehran Stock Exchange. in general, information about companies in capital market accounting to investors and the capital market is considered to be valuable.