Abstract
The main purpose of this article is to determine the impact that Big 4 companies have had after the adoption of IFRS became mandatory and if the level of the fees related to the audit services registered a significant increase. Thus, after a thorough research of the specialized studies, we analyzed the impact of financial reporting according to the International Financial Reporting Standards, determining how the audit fees were influenced and which was the impact of the largest companies targeted in this study. In order to determine the number of companies audited by Big 4, we analyzed all the companies listed on Bucharest Stock Exchange, during the period 2010-2018, which trade premium shares. It is obvious that the financial reporting according to the International Financial Reporting Standards increases the number of companies audited by Big 4, although there has audit fees with higher values. In the following, we will analyze the changes that have occurred in the audit market of Romania.