The brief from the Kaiser Family Foundation shows insurers returning to the levels of profitability seen before the passage of the ACA, but notes recent actions from the Trump administration "cloud expectations for the future."
"Results from mid-2018 suggest that despite significant challenges, the individual market remains stable and insurers are generally profitable," the brief reads, showing no signs of a "market collapse."
Insurers increased premiums for the 2018 plan year, in some cases by double digits, in anticipation of "uncertainty" about what Congress and the administration would do to the ACA and the administration's cancelation of key insurer payments, the brief said.
"Without these policy changes, it is likely that insurers would generally have required only modest premium increases in 2018," the brief said.
But insurers may have overpriced their premiums more than necessary, leading to larger profits.
Because of the overpricing, 2019 premiums aren't expected to increase by much, despite the repeal of the ACA's individual mandate, which takes effect in January, and the administration's expansion of non-ACA plans.
"If not for these policy changes, it is possible that premiums on average could be flat or even decreasing in 2019," reads the brief.
These policies could lead to healthy people dropping out of the market, creating a sicker pool and higher costs for insurers, the brief said.
There is evidence that is already happening, the brief notes, likely because those who don't receive subsidies that help pay for insurance have had to bear the brunt of premium increases, and could decide to forego coverage instead.
"There are indications that the risk pool has become somewhat sicker in the last couple of years, suggesting healthier enrollees may be dropping out of the market," the brief said.
The Trump administration estimates that ACA premiums will drop by an average of 2 percent next year.