OREANDA-NEWS. U.S. life insurers experienced relatively stable earnings in 2015 with flat pretax operating income growth. Earnings were boosted by higher fee income, which offset modestly lower interest margins, unfavorable mortality and a strong U.S. dollar, according to a Fitch Ratings dashboard summarizing GAAP results for U.S. life insurance companies.

"Protracted low interest rates continued to pressure investment yields and while life insurers have largely offset these pressures with prepayment income and strong performance on alternative investments, Fitch expects these offsetting factors to dwindle in 2016," said Dafina Dunmore, Director at Fitch. Dunmore added that "low oil and gas prices and structural changes in the energy market led to impairments in 2015, and is expected to accelerate in 2016."

Average operating return on equity remained relatively flat at 11.9% in 2015 compared with 12.0% in 2014 for Fitch's rated universe. Fixed annuities contributed to interest margin compression while retirement plans and asset management business lines benefited from increased fee income.