This paper examines the use of generative AI at the Securities and Exchange Commission (SEC), focusing on comment letters as a key tool in SEC oversight. Using the AI-detection software GPTZero, it finds that letters with higher AI usage tend to be less extensive. This pattern holds across panel regressions and instrumental variables (IV) analysis. Letters with higher AI usage are more likely to omit important issues, such as revenue recognition topics, indicating that AI is not merely reducing “fluff.” The negative association is stronger when SEC staff are busier and in industries requiring specialized knowledge, but is attenuated or even reversed when review teams have the expertise to use AI effectively. Following the release of ChatGPT in November 2022, coverage increased, especially for smaller firms, highlighting potential benefits of AI. Overall, the study provides early evidence on how generative AI influences regulatory oversight.