Changes in fair value measurements of Level 3 investments during the year ended December 31, 2018, were as follows (in millions): Changes in fair value measurements of Level 3 investments during the year ended December 31, 2017, were as follows (in millions): 118 Private Market Partnerships Insurance Group Annuity Contracts Beginning balance at December 31, 2016 $ 21 $ 2 Actual loss on plan assets: Relating to assets still held at the reporting date (4 ) — Purchases 1 — Sales (1 ) — Transfers out (3) — Ending balance at December 31, 2017 $ 14 $ 2 Private Market Partnerships Insurance Group Annuity Contracts Beginning balance at December 31, 2017 $ 14 $ 2 Actual loss on plan assets: Relating to assets still held at the reporting date (2 ) — Purchases 1 — Sales (6 ) — Ending balance at December 31, 2018 $ 7 $ 2 $^{(e)}$  Includes approximately 27% investments in U.S. domestic government securities, 43% in emerging market government securities and 30% in international government securities. There are no significant foreign currency risks within this classification. $^{(f)}$  Includes limited partnerships that invest primarily in U.S. (94%) and European (6%) buyout opportunities of a range of privately held companies. The pension plan’s master trust does not have the right to redeem its limited partnership investment at its net asset value, but rather receives distributions as the underlying assets are liquidated. It is estimated that the underlying assets of these funds will be gradually liquidated over the next one to ten years. Additionally, the pension plan’s master trust has future funding commitments of approximately $903 million over the next ten years. $^{(g)}$  Investment includes 42% in a collective interest trust investing primarily in short-term securities, 40% in an emerging market 103-12 Investment Trust with investments in emerging country equity securities, 10% in Canadian segregated balanced value, income growth and diversified pooled funds and 8% in a common/collective trust investing in securities of smaller companies located outside the U.S., including developing markets. For some trusts, requests for withdrawals must meet specific requirements with advance notice of redemption preferred. $^{(h)}$  Certain investments that are measured using net asset value per share (or its equivalent) as a practical expedient for fair value have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the notes to the consolidated financial statements. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS OF AMERICAN AIRLINES GROUP INC.