Cigna noticed stop-loss medical costs climbing in the fall, but two-thirds of the stop-loss users renew their coverage in the first of the year, and Cigna did not have time to increase rates for those users, Evanko said.

Related: Voya is doubling stop-loss price increases for 2025

As a result, the ratio of claims to premiums for the full year was somewhere between 90% and 95%, or 4 percentage points to 7 percentage points higher than what Cigna had expected.

Stop-loss insurance accounts for only about 15% of Cigna's health coverage business. For other health insurance lines of business, costs "ran broadly in line with expectations," Evanko said.

Cigna hopes to make up for the impact of the higher costs over the next two years.

"We will do this by balancing pricing action, affordability initiatives, operating cost efficiency, and continued investments," Evanko said.

Stop-loss insurance: Employers use stop-loss arrangements to insure their self-insured benefit plans. Stop-loss can protect an employer against catastrophic losses either at the level of the individual enrollee or at the level of total, planwide, "aggregate" losses.

Segal Group, a New York-based benefits and compensation consulting firm, reported in the summer that 2024 medical stop-loss premiums were 11.5% higher than in 2023.

Voya said its stop-loss increases for 2025 would be about twice as big as the 2024 stop-loss increases.

Cigna executives reported in November that they were basing 2025 employer health coverage prices on the assumption that health care cost increases would be higher than normal.

The earnings: Cigna held the conference call to go over earnings for the fourth quarter.

The Bloomfield, Connecticut-based health insurer is reporting $1.4 billion in net income for the quarter on $66 billion in revenue, up from $1 billion in net income on $51 billion in revenue for the fourth quarter of 2023.

The company ended the year providing or administering health coverage for 19.1 million people, down from 19.8 million people a year earlier.

The pharmacy benefit manager: Cigna is the parent of Express Scripts by Evernorth. Evernorth unit revenue increased to $2.1 billion, from $1.9 billion.

PBMs have taken heat in recent years because some critics have argued that the big PBMs lack transparency and keep much of the value of the prescription drug discounts they negotiate for employers.

Cordani objected to the idea that PBMs cause problems. "Pharmacy benefit managers are essential in helping patients access medications at fair and affordable prices," he said.

But Cordani said Express Scripts will take steps to become more transparent and lower patients' spending on prescriptions even more.

"Going forward, our standard products will provide patients lower prices at the pharmacy counter, protecting them from paying full list prices for drugs, and they will fully benefit from our lower net negotiated prices," Cordani said.

"Next, patients will also have improved predictability, especially and importantly in their deductible phase, by receiving the benefit of Express Scripts negotiated savings like their employer does. We will also expand the benefit summaries and disclosures we provide."

New patient summaries will show a patient's annual total prescription drug costs, the plan paid amounts, and the savings Express Scripts delivers.

"Planned sponsors will also receive an enhanced report beyond what Express Scripts already provides, including additional transparency on costs and pharmacy claim level insights," Cordani said.