Open enrollment ended Friday with 8.7 million people selecting plans, about 500,000 consumers less than the 9.2 million who signed up last year.
This year's enrollment period was more than a month shorter than last year, from November 1 to Dec. 15, compared to Nov. 1 to January 31, 2017, to sign up for 2017 coverage.
For 2018, 2.4 million new consumers chose plans on Healthcare.gov and 6.3 million people renewed, for a total 8.7 million getting coverage through the Affordable Care Act.
ACA enrollment this year has been challenged by the shortened sign-up period, a 90 percent cut in the promotional budget, a reduction in the amount of money going to navigator organizations which help consumers choose plans, GOP legislative attempts to repeal President Obama's signature legislation and premium increases.
Numerous insurers have pulled out of the ACA market citing financial losses and lack of stability. The Trump Administration ended cost-sharing reduction payments to insurers and the new tax bill got rid of the individual mandate to get coverage.
Enrollment this year and last falls short of the 9.6 million consumers who signed up for 2016 coverage.
The Centers for Medicare and Medicaid Services said it expected in March to release a more detailed report that includes plan selections across the state-based exchanges.