This paper focuses on audit market concentration of listed firms which is characterized by an oligopoly of “Big Four” audit firms. Hence a state of the art analysis of the status quo of concentration measurement has been conducted on the audit market from an international perspective....

This article discusses the interdiction of combining audit and not audit services by the external auditor, which the EU Commission (EC) is presently discussing as reform measures in its regulation draft of November 30, 2011. According to an agency-theoretical definition of the auditor's function...