When a company rotates auditors but has non-audit contracts with two other Big Four firms, there is a reduced level of competition for audit services. This is because the remaining firms may be restricted from taking the audit role due to conflicts of interest. As a result, the selection process may not be fully competitive, leading to a "sub-optimal level of competition."

Regulatory frameworks, such as the EU Audit Reform and the Sarbanes-Oxley Act, encourage audit firm rotation to enhance independence and objectivity. However, conflicts from existing advisory relationships can limit viable audit candidates.