When agencies release information on a Friday afternoon, it is generally because of unfavorable news they hope will lose potency over the weekend. On Friday, the Department of Health and Human Services (HHS) released 2015 end-of-the-year exchange enrollment data. After reviewing the numbers, it is understandable why HHS would want this release to attract as little attention as possible.

Most news stories reporting the numbers have focused on the large overall decline in exchange enrollment throughout 2015—down 25% from the number of people who selected a plan at the end of open enrollment—or how the end-of-the-year number failed to meet even HHS’ downgraded target. The most striking number from the data, however, is the large drop in exchange enrollment—equal to about 1.13 million people—during the last six months of the year. As I explain below, this large net decline is problematic for the future of the Affordable Care Act (ACA) as it likely exacerbates other adverse selection problems induced by the law.