UnitedHealth Group Inc., the largest U.S. health insurer, said its rates for ObamaCare plans in New York may be too low because the failure of a competing insurer last year might lead to shortfalls in payments designed to stabilize Obamacare markets.

In states like New York, health insurers participating in ObamaCare negotiate annually with regulators to set prices for coverage. UnitedHealth’s rates were set anticipating risk-sharing payments designed to stabilize the new insurance markets, William Golden, the company’s northeast region chief executive officer, said Wednesday. If the loss of a participant reduces the funds available to UnitedHealth, the company’s rates in New York’s ObamaCare market may be insufficient, he said.

For the first time, businesses that employ the equivalent of 50 to 99 full-time workers face a fine of $2,160 per worker if they don’t provide coverage. (An employer’s first 30 workers are excluded from the calculation.)

For an employer with the equivalent of 75 full-time workers, for example, the maximum penalty would be $97,200 for 2016.

A growing number of people are turning to health-care ministries to cover their medical expenses instead of buying traditional insurance, a trend that could challenge the stability of the Affordable Care Act (ACA).

The ministries, which operate outside the insurance system and aren’t regulated by states, provide a health-care cost-sharing arrangement among people with similarly held beliefs. Their membership growth has been spurred by an ACA provision allowing participants in eligible ministries to avoid fines for not buying insurance.

Ministry officials estimate they have about 500,000 members nationwide, more than double the roughly 200,000 members before the law was enacted in 2010.

Obama administration officials said last month that about 2.5 million new customers had bought insurance through HealthCare.gov since open enrollment began on Nov. 1. The number of new enrollees is 29% higher than last year at this time, suggesting that the threat of a larger penalty may be motivating more people to get covered.

But plenty of healthy holdouts remain, and their resistance helps explain why insurers are worried about the financial viability of the exchanges over time. People who earn too much to qualify for federal subsidies that defray the cost of coverage may be most likely to opt out.

A group of health policy analysts have collaborated on a set of proposals for replacing the Affordable Care Act (ACA) and also reforming other major portions of health care delivery, such as the tax treatment of employer-sponsored health insurance, Medicaid, Medicare, and Health Savings Accounts. Because so much attention has been paid to the repeal of the ACA by those who have opposed it, we believe it is important to focus on a serious proposal that could both replace this law and provide additional measures of reform, especially to the health care entitlement programs.

We believe our reform agenda represents such a proposal. Furthermore, none of us regards the pre-ACA health care system as an acceptable alternative.

Only 7% of the uninsured correctly identify this as the deadline to enroll in coverage and 20% say they have been contacted by someone about signing up for coverage. When asked why they have not purchased health insurance this year, nearly half of the uninsured (46%) say they have tried to get coverage but that it was too expensive.

Consumers anxious to beat the midnight Tuesday deadline to enroll on the federal insurance exchange overwhelmed call center lines Monday, federal officials said. Some people were being asked to leave their names so they could be called back after the deadline to be enrolled. The Centers for Medicare and Medicaid Services said they would still be able to have coverage effective Jan. 1 if they left their contact information before the deadline.

HealthSpan, the insurance arm of Catholic health system Mercy Health, is getting rid of its medical group and halting sales of ObamaCare policies just two years after acquiring Kaiser Permanente’s Ohio subsidiary. Spokesman Chuck Heald said HealthSpan will stop selling individual and small-group health plans on the ObamaCare exchanges to focus more on Medicare and employer plans. HealthSpan jacked up premium rates for 2016 individual and small-group plans anywhere from 9% to 32% to account for the sicker-than-expected exchange population.

UnitedHealth Group won’t pay brokers commissions on sales of individual health plans in most states where it participates in Obamacare exchanges, a move that will likely discourage market demand for its plans in those states. The News & Observer reports the Minnetonka-based insurance giant notified North Carolina brokers of the policy change Friday, not long after it announced plans to evaluate whether it would continue to serve the public exchange markets after 2016.

About 4,500 Medical University of South Carolina patients currently covered by Consumers’ Choice Health Plan need to pick a new policy by Tuesday to remain insured on Jan. 1. Medical University Hospital CEO Pat Cawley told the MUSC Board of Trustees on Thursday that the announcement created “an administrative nightmare.”

Only 35% of 67,000 Consumers’ Choice customers across the state have selected a new plan so far.