Voluntary Audits versus Mandatory Audits
利用英国私营公司从强制审计转为自愿审计的自然实验，研究发现自愿接受审计的公司因传递积极信号而获得信用评级上调，而放弃审计的公司则因负面信号和失去保证价值而评级下调。
ABSTRACT Exploiting a natural experiment in which voluntary audits replace mandatory audits for U.K. private companies, we analyze whether imposing audits suppresses valuable information about the types of companies that would voluntarily choose to be audited. We control for the assurance benefits of auditing to isolate the role signaling plays by focusing on companies that are audited under both regimes. These companies experience no change in audit assurance, although they can now reveal for the first time their desire to be audited. We find that these companies attract upgrades to their credit ratings because they send a positive signal by submitting to an audit when this is no longer legally required. In contrast, companies that dispense with being audited suffer downgrades to their ratings because avoiding an audit sends a negative signal and removes its assurance value. Data Availability: All data are available from public sources.