RT Journal Article SR Electronic T1 Individual Market Volatility and Vulnerability, 2015 to 2019 JF RSF: The Russell Sage Foundation Journal of the Social Sciences FD Russell Sage Foundation SP 206 OP 222 DO 10.7758/RSF.2020.6.2.09 VO 6 IS 2 A1 Jean Marie Abraham YR 2020 UL http://www.rsfjournal.org/content/6/2/206.abstract AB The Affordable Care Act (ACA) introduced large changes to the individual market for health insurance. Using 2015–2019 HIX Compare and geographic-specific data, this study examines the volatility and vulnerability of local insurance markets using insurer participation and premium information. The study also examines how markets with higher volatility and vulnerability differ from others with respect to demographics, labor market conditions, health status, provider supply, and state policies. Entry and exit patterns suggest decreasing volatility, but forty-eight million Americans reside in markets that are vulnerable, given limited competition and high premiums.