NOTES TO CONSOLIDATED FINANCIAL STATEMENTS OF AMERICAN AIRLINES GROUP INC. Balance Sheet Position $^{(1)}$  The 2019 and 2018 pension actuarial (gain) loss primarily relates to changes in our weighted average discount rate and mortality assumption and, in 2018, changes to our retirement rate assumptions. $^{(2)}$  The 2019 retiree medical and other postretirement benefits actuarial loss primarily relates to changes in our weighted average discount rate assumption and plan experience adjustments. The 2018 retiree medical and other postretirement benefits actuarial gain primarily relates to changes in our weighted average discount rate, medical trend and per capita claims assumptions. Pension Benefits Retiree Medical and  Other Postretirement Benefits 2019 2018 2019 2018 (In millions) Fair value of plan assets at beginning of period $ 10,053 $ 11,395 $ 225 $ 295 Actual return (loss) on plan assets 2,305 (1,151) 41 (24) Employer contributions  (3) 1,230 475 12 35 Settlements (2) (4) — — Benefit payments (689 ) (662 ) (74 ) (81 ) Fair value of plan assets at end of period $ 12,897 $ 10,053 $ 204 $ 225 Funded status at end of period $ (5,461 ) $ (6,325 ) $ (620 ) $ (612 ) $^{(3)}$  During 2019, we contributed $1.2 billion to our defined benefit pension plans, including supplemental contributions of $444 million and a $786 million minimum required contribution. During 2018, we contributed $475 million to our defined benefit pension plans, including supplemental contributions of $433 million and a $42 million minimum required contribution. 99 Pension Benefits Retiree Medical and  Other Postretirement Benefits 2019 2018 2019 2018 (In millions) As of December 31, Current liability $ 5 $ 7 $ 24 $ 23 Noncurrent liability 5,456 6,318 596 589 Total liabilities $ 5,461 $ 6,325 $ 620 $ 612 Net actuarial loss (gain) $ 5,680 $ 5,356 $ (426 ) $ (452 ) Prior service cost (benefit) 104 131 (120) (362) Total accumulated other comprehensive loss (income), pre-tax $ 5,784 $ 5,487 $ (546 ) $ (814 )