This paper examines how audit oversight by a public-sector regulator affects investors' assessments of reporting credibility. We analyze whether market responses to unexpected earnings releases increase following the introduction of the Public Company Accounting Oversight Board (PCAOB), as predicted by theory if the new regime enhances reporting credibility. To identify the effects, we use a difference-in-differences design that exploits the staggered introduction of the inspection regime, which affects firms at different points in time depending on their fiscal year-ends, auditors, and the timing of PCAOB inspections. We find that market responses to unexpected earnings increase significantly following the introduction of the PCAOB inspection regime. Corroborating these findings, we also find an increase in abnormal volume responses to firms' 10-K filings after the new regime is in place. Overall, our results are consistent with public audit oversight increasing the credibility of financial reporting.
Brandon Gipper
IntroductionAs the accounting scandals in the early 2000s illustrated, reliable financial reporting is a cornerstone of trust in the stock market, which in turn plays a key role for investor participation (Guiso et al., 2008). In an effort to restore trust in financial reporting after the scandals, the U.S.Congress passed the Sarbanes-Oxley Act (hereafter, "SOX"). One of its core provisions was the creation of the Public Company Accounting Oversight Board (hereafter, the "PCAOB") and the requirement that the PCAOB inspect all audit firms (hereafter, "auditors") of SEC-registered public companies (hereafter, "firms" or "issuers"). The introduction of the PCAOB represents a major regime shift in auditing, replacing self-regulation with public oversight. For these reasons, the effect of the new PCAOB regime on reporting credibility is not obvious. Another complication is that investors should respond negatively to restatements or the revelation of deficiencies in the audits of particular engagements or particular auditors. It is only if these outcomes indicate improvements in audit quality going forward, spilling over to other engagements and auditors and hence leading to broader improvements in audit quality, that we expect reporting credibility to increase. In this regard, it helps that the PCAOB does not reveal which audit engagements were inspected, but produces a number of publicly observable outcomes, notably auditor-level inspection reports, which allow investors to form updated assessments of the PCAOB regime. Similarly, investors can potentially draw inferences about the new regime from observed changes in corporate reporting (such as restatements).The hypothesized mechanism for a link between public audit oversight and reporting credibility is that PCAOB inspections identify meaningful deficiencies in the way audits are conducted, leading to subsequent improvements in auditing procedures that extend beyond a single engagement. Investors learn about these broader changes and adjust th...