OBJECTIVES: The Affordable Care Act established federal and state health insurance exchanges to expand access to affordable medical coverage. This research reviews data on rates of switching among reenrollees on the federally facilitated marketplace (FFM) and select state-based marketplaces (SBMs) to characterize member turnover. We then consider how health care payers are assessing pharmacoeconomic value which may accrue over the long term in the presence of exchange business.METHODS: Secondary research reviewed exchange enrollment data to understand levels of switching and how they compare to other lines of business. Twenty five health care payers responsible for pharmacy benefit management were surveyed to understand whether and how perceptions and assessment of pharmacoeconomic value are affected by turnover on exchange plans. Respondents represented managed care, pharmacy benefit management and integrated systems, including organizations both with and without exchange business (for comparison).RESULTS: During the 2015 (second) open enrollment period for the FFM, 29% of all reenrollees (54% of active reenrollees) switched marketplace plans. SBMs have shown locally much higher rates of switching. Turnover significantly exceeds historical benchmarks for other lines of business. Surveyed payers recognize exchange products as “high churn” and several believe that they are driving more shortsighted expectations for accrual of anticipated long-term cost offsets attributable to pharmaceutical innovation. CONCLUSIONS: In the US, it can be challenging for manufacturers to substantiate the long term value of treatment innovation to payers due to turnover among insured populations. High rates of switching on the health insurance exchanges may exacerbate this challenge. Strategic options for addressing the issue will vary depending upon the differential characteristics of the disease area and intervention. Achieving highest possible rates of treatment across fragmented exchange populations should help to ensure that long-term cost offsets are fairly realized by competing insurers, even as beneficiaries switch between plans.