INDIANAPOLIS — Managed care provider Cigna Corp. said Monday the slumping economy has forced it to cut roughly 1,100 jobs as it deals with employer customers who also are making cuts and reducing the number of people covered by insurance.

The Philadelphia-based insurer will cut about 1,000 U.S. positions and 100 outside the United States. The layoffs amount to about 4 percent of its work force, which totals roughly 28,000 people.

"All of our customers, they're reducing their work forces, and they need to reduce costs," Cigna spokesman Chris Curran said. "In order for us to be as efficient and as competitive as possible, we've got to manage costs."

Cigna has said it expects about a 2 percent decline this year in membership, which stood at 11.9 million people at the end of last year's third quarter.

The insurer is still analyzing the job cuts and working to decide from which parts of the company they will come, Curran said.

"We think most of this will be completed by midyear," he said.

Cigna also plans to close some locations and sell property but hasn't decided the specifics on that, either.

Cigna will take an after-tax charge of between $30 million and $40 million in the recently completed fourth quarter related to the moves. About 85 percent of that charge will be from severance packages offered to employees, Curran said. Those will be based, in part, on a person's job and years of service with the company.

Cigna Chairman and Chief Executive H. Edward Hanway said in a statement his company's actions were essential "given the unprecedented economic situation we and our customers are facing."

Cigna joins competitors Aetna Inc. and UnitedHealth Group Inc. in trimming staff. Aetna, based in Hartford, Conn., said last month it would cut 1,000 jobs, or nearly 3 percent of its work force, due to the slumping economy.

UnitedHealth, based in Minnetonka, Minn., announced plans to cut 4,000 jobs last July.

Cigna shares closed at $18.15 Monday, up 2 percent, or 36 cents, from the previous close. The job cuts were announced at 5 p.m., after the markets closed.