The Centers for Medicare and Medicaid Services (CMS), the federal agency that runs the web-based health insurance supermarket program, says 823,180 people chose coverage through the system during the week that ended Saturday.
Those people were on track to have a private coverage purchased through HealthCare.gov in place starting Jan. 1, 2018.
The system has received plan selection information for a total of 3.6 million people.
Because CMS reported activity data for the open enrollment period for 2017 every two weeks, making year-over-year comparisons is difficult.
An Affordable Care Act exchange is a web-based system that sells individual and small-group health coverage from private insurers.
The U.S. Department of Health and Human Services set up HealthCare.gov to provide ACA exchange account setup and administration services for states that are unwilling or unable to provide those services.