Abstract The concentration of the audit market has been of interest for several years as the dominance of a few companies has always been an issue of debate. The need or not to address this situation, the reasons that cause it, any possible risks assessed and solutions to reduce them have been addressed by a wide range of studies. Our research seeks to examine the structure of the Romanian Audit Market for listed entities, both before and following the recently adopted European Union Audit Reform. The main purpose is to understand the market structure, identify some of the main factors that influence auditor choice and if there was any impact following the new directive. The analyses focused on 74 listed companies, for the period from 2013 to 2022, for which we collected the relevant data in order to analyze the audit market structure, its evolution following the new audit directive and, using linear regressions models, test the influence that size, share class category, existence of long-term debt, shareholder type, evidence of shareholder direct involvement and auditor office location has on choosing one of the Big 4 auditors or not. Our analysis showed that Big4 auditors ecreased in market share especially after 2016, the date the new audit reform came into effect, from 49% to 41% and that the number of auditor changes increased significantly after this date. We also found that the number of cases where another Big4 auditor was selected decreased from 64%, in the period from 2013-2016, to only 28%, in the period from 2017-2022. These findings support therefore the assumed existence of an impact in the market following the latest European Union audit directive. The linear regression analysis performed showed no significant influence for the variables analyzed, when it comes to choosing a Big4 Auditor, the highest coming from the share class variable (26%) and size (12%). Even though our paper offers some light regarding the audit market for listed companies in Romania and the evolution following the new directive further research is needed to better understand client behavior and what influences auditor choice.