All pension plan assets in the U.S. are invested through a single master trust fund. The strategic asset allocation for this trust fund is approved by management. The general principles guiding U.S. pension asset investment policies are those embodied in the Employee Retirement Income Security Act of 1974 ("ERISA"). These principles include discharging Historical DuPont's investment responsibilities for the exclusive benefit of plan participants and in accordance with the "prudent expert" standard and other ERISA rules and regulations. Historical DuPont establishes strategic asset allocation percentage targets and appropriate benchmarks for significant asset classes with the aim of achieving a prudent balance between return and risk. Strategic asset allocations in other countries are selected in accordance with the laws and practices of those countries. Where appropriate, asset liability studies are utilized in this process. U.S. plan assets and a portion of non-U.S. plan assets are managed by investment professionals employed by Historical DuPont. The remaining assets are managed by professional investment firms unrelated to the company. Historical DuPont's pension investment professionals have discretion to manage the assets within established asset allocation ranges approved by management of the company. Additionally, pension trust funds are permitted to enter into certain contractual arrangements generally described as "derivatives". Derivatives are primarily used to reduce specific market risks, hedge currency and adjust portfolio duration and asset allocation in a cost-effective manner. In connection with pension contributions of $2,900 million to its principal U.S. pension plan during the period of January 1, 2017 through August 31, 2017, an investment policy study was completed for the principal U.S. pension plan. The study resulted in new target asset allocations being approved for the U.S. pension plan with resulting changes to the expected return on plan assets. The long-term rate of return on assets decreased from 8 percent to 6.25 percent. The weighted-average target allocation for plan assets of the company's pension plans is summarized as follows: Global equity securities include varying market capitalization levels. U.S. equity investments are primarily large-cap companies. Global fixed income investments include corporate-issued, government-issued and asset-backed securities. Corporate debt investments include a range of credit risk and industry diversification. U.S. fixed income investments are weighted heavier than non-U.S. fixed income securities. Other investments include cash and cash equivalents, hedge funds, real estate and private market securities such as interests in private equity and venture capital partnerships. F-67 Target Allocation for Plan Assets December 31, 2018 December 31, 2017 Asset Category U.S. equity securities 19 % 17 % Non-U.S. equity securities 16 18 Fixed income securities 50 50 Hedge funds 2 2 Private market securities 8 8 Real estate 3 3 Cash and cash equivalents 2 2 Total 100% 100% Estimated Future Benefit Payments at December 31, 2018 Defined Benefit Pension Plans Other Post Employment Benefits (In millions) 2019 $ 1,648 $ 240 2020 1,613 235 2021 1,597 226 2022 1,574 219 2023 1,556 210 Years 2024-2028 7,437 861 Total $ 15,425 $ 1,991 Plan Assets The estimated future benefit payments, reflecting expected future service, as appropriate, are presented in the following table: Estimated Future Benefit Payments E. I. du Pont de Nemours and Company Notes to the Consolidated Financial Statements (continued)