States have flexibility in implementing the Affordable Care Act's health insurance marketplaces and may choose to become more (or less) involved in marketplace operations over time. Interest in new implementation approaches has increased as states seek to ensure the long-term financial stability of their exchanges and exercise local control over marketplace oversight. This brief explores the experiences of four states—Idaho, Nevada, New Mexico, and Oregon—that established their own exchanges but have operated them with support from the federal HealthCare.gov eligibility and enrollment platform. Drawing on discussions with policymakers, insurers, and brokers, we examine how these supported state-run marketplaces perform their key functions. We find that this model may offer states the ability to maximize their influence over their insurance markets, while limiting the financial risk of running an exchange.