This research examines the legal analysis of implementing the Full Periodic Call Auction (FPCA) mechanism on the Special Monitoring Board of the Indonesia Stock Exchange (IDX) with a focus on investor protection. The FPCA is a trading system designed to improve market fairness and transparency by consolidating orders at specific intervals, contrasting with the continuous auction system. The study aims to address two main issues: (1) How can FCA be a form of legal protection for Investors in the Indonesian Capital Market and (2) How is the comparison of the application of the FCA in the Indonesian Capital Market and the Singapore Capital Market in the aspect of protection of Investors. This study adopts a normative-empirical juridical method by analyzing legislation, regulatory frameworks, and secondary data such as academic literature, existing case examples and official reports. Data collection was conducted through document analysis, focusing on relevant Indonesian laws, Financial Services Authority (OJK) regulations, and the rules of the Indonesia Stock Exchange. The data were analyzed qualitatively to provide an in-depth understanding of the legal implications of the FPCA mechanism. FPCA minimizes price volatility and mitigates market manipulation by providing a transparent and structured trading environment. In conclusion, while the FPCA mechanism represents a progressive approach to enhancing market integrity and investor protection, its implementation requires robust legal and institutional support. Strengthening investor awareness and ensuring compliance with relevant regulations are critical to realizing the full potential of FPCA in the Indonesian capital market. This research contributes to the discourse on legal and regulatory measures in capital market operations, emphasizing the importance of balancing market innovation with investor protection.