Table of Contents INVESTMENTS Net Investment Income The significant components of Net investment income are presented in the following table. Fixed income securities, as presented, include both fixed maturity securities and non-redeemable preferred stock. Years ended December 31 (In millions) 2018 2017 2016 Fixed income securities: Taxable fixed income securities $ 1,449 $ 1,397 $ 1,421 Tax-exempt fixed income securities 384 427 405 Total fixed income securities 1,833 1,824 1,826 Limited partnership and common stock investments (42 ) 207 158 Other, net of investment expense 26 3 4 Pretax net investment income $ 1,817 $ 2,034 $ 1,988 Fixed income securities, after tax $ 1,512 $ 1,324 $ 1,315 Net investment income, after tax 1,500 1,462 1,427 Effective income yield for the fixed income securities portfolio, pretax 4.7 % 4.7 % 4.8 % Effective income yield for the fixed income securities portfolio, after tax 3.9% 3.4% 3.5% Pretax net investment income decreased $217 million in 2018 as compared with 2017. The decrease was driven by limited partnership and common stock investments, which returned (1.9)% in 2018 as compared with 9.1% in the prior year. The lower return in 2018 included the change in fair value of common stock investments. See Note A to the Consolidated Financial Statements included under Item 8 for further information regarding the treatment of the change in fair value of common stock investments. Despite the decline in limited partnership income, net investment income, after tax, increased $38 million in 2018 as compared with 2017 driven by the lower Federal corporate income tax rate. Pretax net investment income increased $46 million in 2017 as compared with 2016. The increase was driven by limited partnership and common stock investments, which returned 9.1% in 2017 as compared with 6.4% in the prior year. 42