UnitedHealth Group Inc. on Tuesday raised its outlook for 2018 earnings per share by more than 16 percent due to the U.S. corporate tax cuts and said it would speed up investments in data analytics and technology to better serve consumers.

UnitedHealth is the largest U.S. health insurer and the first to report fourth-quarter earnings, which it said rose to $2.59 per share, beating analyst expectations of $2.51 per share.

"We think many investors were worried there could be greater reinvestment and other offsets limiting the tax benefit and we expect the market to react favorably to the updated guidance," Evercore ISI analyst Michael Newshel said in a research note.

Shares of the largest U.S. health insurer rose about 1 percent to $231.65 in premarket trading on Tuesday after closing at $228.64 on Friday.

The company said it now expects 2018 full-year net earnings per share forecast range to be between $11.65 and $11.95, up from its prior forecast of $10.00 to $10.30 per share.

Excluding items, it sees 2018 earnings of $12.30 to $12.60 per share, compared to a previous outlook of $10.55 to $10.85 per share.

Corporate earnings in 2018 are expected to see a boost from the sweeping $1.5 trillion tax bill that President Donald Trump signed into law last month.

The health insurer said net earnings attributable to shareholders more than doubled to $3.62 billion, or $3.65 per share, in the quarter ended Dec. 31, from a year earlier.

The quarterly earnings included a one-time tax benefit of $1.21 per share. Excluding items, UnitedHealth earned $2.59 per share, beating analyst estimates of $2.51 per share.

Total revenue rose 9.5 percent to $52.06 billion, driven by growth across UnitedHealth's businesses.

Analyst on an average were expecting revenue of $51.5 billion, according to Thomson Reuters I/B/E/S.

Revenue from the company's Optum business, which manages drug benefits and offers healthcare data analytics services, rose 10 percent to $24.39 billion.