Using the introduction of insider selling regulation as a policy shock, this study examines the impact of regulatory intervention on auditors’ risk perceptions based on a sample of A-share listed companies from 2010 to 2022. The findings indicate that, following the implementation of the regulation, auditors charge significantly higher fees to clients with insider selling. Mechanism tests show that increased investor attention serves as an important channel through which the regulation affects audit pricing. Moderating effect analysis reveals that the increase in audit fees is more pronounced for newly undertaken audit engagements, clients without audit committee interlocking relationships, and audit firms that rank higher among the top 100 and have stronger industry expertise. Further analysis demonstrates that audit premiums are higher when large shareholders and directors, supervisors, and senior executives engage in insider selling during the same period, or when the cumulative scale of insider selling is larger. However, auditors fail to identify the opportunistic motives behind insider selling. The regulation also increases the probability that clients with insider selling receive non-standard audit opinions and that their audit engagements are terminated.