NOTES TO CONSOLIDATED FINANCIAL STATEMENTS - Continued Unum Group and Subsidiaries Note 3 - Investments - Continued Net Investment Income Net investment income reported in our consolidated statements of income is as follows: $^{1}$ The net unrealized gain recognized in net investment income for the year ended December 31, 2019 related to equity securities still held at December 31, 2019 was $3.3 million. The net unrealized loss recognized in net investment income for the year ended December 31, 2018 related to equity securities still held at December 31, 2018 was $3.9 million. $^{2}$ The net unrealized gain recognized in net investment income for the year ended December 31, 2019 related to private equity partnerships still held at December 31, 2019 was $6.8 million. The net unrealized gain recognized in net investment income for the year ended December 31, 2018 related to private equity partnerships still held at December 31, 2018 was $7.1 million. Realized investment gains and losses are as follows: 145 Realized Investment Gain and Loss Year Ended December 31 2019 2018 2017 (in millions of dollars) Fixed Maturity Securities $ 2,213.6  $ 2,239.7  $ 2,271.8  Derivatives 73.4  66.1  56.4  Mortgage Loans 103.3  110.1  104.2  Policy Loans 19.9  18.6  17.9  Other Long-term Investments Equity Securities 1 5.6  (0.2) 1.5  Private Equity Partnerships 2 31.7  36.0  25.5  Other 3.7  8.4  10.0  Short-term Investments 29.0  23.7  11.3  Gross Investment Income 2,480.2  2,502.4  2,498.6  Less Investment Expenses 32.1  35.2  32.8  Less Investment Income on Participation Fund Account Assets 12.8  13.5  14.1  Net Investment Income $ 2,435.3  $ 2,453.7  $ 2,451.7  Year Ended December 31 2019 2018 2017 (in millions of dollars) Fixed Maturity Securities Gross Gains on Sales $ 22.9  $ 9.7  $ 13.8  Gross Losses on Sales (32.6) (15.2) (4.4) Other-Than-Temporary Impairment Loss (25.3) (17.5) (8.1) Mortgage Loans and Other Invested Assets Gross Gains on Sales 4.6  0.5  9.4  Gross Losses on Sales (0.3) —  (0.2) Impairment Loss —  (1.4) (0.9) Embedded Derivative in Modified Coinsurance Arrangement 8.3  (15.2) 30.8  All Other Derivatives (0.1) 0.3 (0.1) Foreign Currency Transactions (0.7) (0.7) —  Net Realized Investment Gain (Loss) $ (23.2) $ (39.5) $ 40.3 