Oil and gas investment disputes often arise from corporate structures built around special purpose vehicles, joint ventures, project finance, and layered ownership chains. When a host state terminates a concession, revokes a license, alters fiscal terms, or intervenes in regulation, the immediate legal injury is usually suffered by the locally incorporated project company. Yet the same injury is transmitted economically to foreign shareholders through diminished share value and lost dividends. This phenomenon, known as reflective loss, places investor–State arbitration between two legal logics. Methodologically, the study adopts a doctrinal and case-law-based approach, interpreting treaty text and leading arbitral awards together with corporate-law rationales and sector-specific investment structures. Corporate law normally treats the company as the proper claimant for harm to corporate assets, while investment treaty law frequently protects shares as investments and permits shareholders to bring claims in their own name. The resulting tension is especially acute in the hydrocarbon sector, where the same project may generate contractual claims by the operating company, treaty claims by direct and indirect shareholders, and parallel proceedings by consortium participants. This article argues that reflective loss should not be treated as a simple jurisdictional defect. Instead, it should be managed as a system design problem through a structured approach that characterizes the loss, controls procedural multiplicity, and disciplines remedies. The proposed framework seeks to preserve treaty protection while preventing double recovery and incoherent awards in oil and gas arbitration.