UnitedHealth Group shares dipped in after-hours trading Monday on news that the managed health-care giant issued a disappointing earnings forecast.

Shares dropped more than 2 percent in trading after the bell, before regaining ground. Shares were recently down about 1.5 percent.

UnitedHealth projected revenue for 2018 that would be only marginally higher than most earlier analyst estimates, which called for revenue of $218 billion next year.

The company estimates revenue will be between $223 billion and $225 billion for 2018.

UnitedHealth projected adjusted net earnings of $10.55 to $10.85 per share for next year. Analysts on average had estimated the company's adjusted net earnings would be $10.81 per share in 2018.

Net earnings would be between $10 and $10.30 per share next fiscal year, the company said.

UnitedHealth also said it expects revenue for fiscal year 2017 will exceed $200 billion, with adjusted net earnings approaching $10 per share. According to Thomson Reuters, the company was expected to earn $9.99 a share, on an adjusted basis, on revenue of $200 billion.

UnitedHealth expects net earnings to approach $9.45 per share.

Cash flows from operations are projected to be in the range of $13.3 billion to $13.8 billion in 2018, the company said.