美联储-作为长期资产负债表构成的考虑因素，中央银行对市场运作资产购买的准备情况（英）

Finance and Economics Discussion SeriesFederal Reserve Board, Washington, D.C.ISSN 1936-2854 (Print)ISSN 2767-3898 (Online)Central bank preparedness for market-functioning asset purchasesas a consideration for long-run balance sheet compositionRochelle M. Edge and Dan Li2025-077Please cite this paper as:Edge, Rochelle M., and Dan Li (2025). “Central bank preparedness for market-functioningasset purchases as a consideration for long-run balance sheet composition,” Finance andEconomics Discussion Series 2025-077.Washington: Board of Governors of the FederalReserve System, https://doi.org/10.17016/FEDS.2025.077.NOTE: Staff working papers in the Finance and Economics Discussion Series (FEDS) are preliminarymaterials circulated to stimulate discussion and critical comment. The analysis and conclusions set forthare those of the authors and do not indicate concurrence by other members of the research staff or theBoard of Governors. References in publications to the Finance and Economics Discussion Series (other thanacknowledgement) should be cleared with the author(s) to protect the tentative character of these papers. 1 Central bank preparedness for market-functioning asset purchases as a consideration for long-run balance sheet composition1 Rochelle M. Edge and Dan Li August 2025 Abstract This paper proposes an approach to enhance the Federal Reserve's readiness to undertake market-functioning asset purchases during Treasury market disruptions. It notes that by tilting the SOMA Treasury portfolio toward bills rather than maintaining a maturity structure proportionate to that of outstanding Treasury debt—often viewed as the most neutral portfolio—the Fed can create a larger volume of reinvestments each month that can serve as a “war chest” for undertaking market-functioning asset purchases. This structure of the SOMA Treasury portfolio enables market-functioning asset purchases to be made without expanding the balance sheet or increasing reserves. This avoids the need for close monitoring of reserves when asset purchases are eventually unwound, while also allowing for a clearer differentiation between asset purchases undertaken to support market functioning and asset purchases undertaken to ease financial conditions. Under reasonable assumptions, bills portfolio shares ranging up to around 40 percent—that is, twice that of the 20 percent proportionate portfolio—could be desirable. We also consider approaches for restoring the SOMA Treasury portfolio and, thereby war chest, back to its pre-stress composition. We find that, if the full monthly war chest is depleted to undertake market functioning purchases, restoring it to its pre-stress composition by allowing purchased coupon securities to mature and reinvesting these proceeds into bills, would take 2½ to 5½ years. These lengthy timeframes would limit for many years the Federal Reserve’s ability to respond to Treasury market disruptions without expanding its balance sheet. 1. Introduction The severe