A major insurer is preparing for the worst in its Obamacare business next year, as it warily remains committed to the law's exchanges.

Cigna, during an earnings call Thursday, outlined its footprint in the Obamacare exchanges for 2017, as other major insurers have shrunk their presence on the exchanges due to financial problems.

"We are going to expect to see some revenue growth but we are continuing to plan for a loss," CEO David Cordani said.

Cordani said Cigna had planned to expand its presence on the exchange by growing from seven markets to 10, but decided to scale that back.

Instead, it reduced its offerings in three markets and will expand into three new markets, Cordani said.

He noted that Cigna is still looking into Obamacare's exchanges to see "whether there is a sustainable future there."

Several major insurers decided to reduce their Obamacare offerings for 2017 due to major losses.

UnitedHealth announced it will leave most of the 34 states it offers plans in for 2017 after expecting losses of more than $600 million. Aetna also announced it will exit 70 percent of the exchanges it offers plans on next year.

Humana will slightly reduce its offerings, pulling out of four out of 15 states.

Another major insurer, Anthem, has remained committed to the law's exchanges. However, the insurer's CEO recently said that changes need to be made in 2018 for continued participation, including delaying or repealing a health insurance tax.

Cigna's announcement comes two days after 2017 open enrollment started, which goes until Jan. 31.

Insurers are raising Obamacare premiums by an average 25 percent next year to handle higher medical claims due to a sicker enrollee population.

The administration has countered news of the high premiums by noting that about 85 percent of enrollees can receive subsidies to pay down the cost of insurance.