Market reaction to auditor switching from big 4 to third-tier small accounting firms

After the demise of Arthur Andersen, the public accounting industry has witnessed a significant migration of public clients to second-tier (Grant Thornton and BDO Seidman) and smaller third-tier accounting firms. While prior literature documents that smaller auditors are perceived by the stock market as an inferior substitute for a Big 4 auditor, this perception appears to have changed in recent years. In this paper, we analyze market responses to auditor switching from Big 4 to smaller accounting firms during 2002 to 2006. We break our sample period into two separate periods (Periods 1 and 2) based on when regulatory changes occurred. These changes included Sarbanes-Oxley (SOX) 404 implementation, Public Company Accounting Oversight Board (PCAOB) inspections, and a tightened Form 8-K filing deadline. We find a relatively more positive stock market reaction to clients switching from a Big 4 to a smaller third-tier auditor in Period 2. This relatively more positive reaction in Period 2 reflects companies seeking better services rather than a lower audit fee, when an audit quality drop is less likely. Overall, our results suggest that companies and investors have become more receptive to smaller accounting firms.