OpenAI expanded its ecosystem in January 2024 with the launch of its new transformative GPT Store (Store) that allows subscribers to use and share custom chatbots. The standalone GPTs in the Store have capabilities for tasks like booking flights, summarizing a collection of PDFs or assisting negotiations – extending beyond the preloaded ChatGPT and DALL‑E functions. In just a few months, the Store has attracted three million GPTs. This article examines the Store’s top security issues, including sizable third-party perils, and identifies key priorities for compliance professionals and company engineers for mitigating the risks of the new GPT app marketplace. It also suggests resources for compliance professionals to monitor security concerns around large language models. See our two-part series on managing legal issues arising from use of ChatGPT and Generative AI: “Managing Legal Issues Arising From Use of ChatGPT and Generative AI: E.U. and U.S. Privacy Law Considerations” (Apr. 12, 2023), and “Industry Considerations and Practical Compliance Measures” (Apr. 26, 2023).