2025-05-20-IMF-测试美国国债回购计划的流动性支持效应（英）_43页_2mb

The U.S. Treasury introduced the liquidity support buyback program in May 2024 to enhance market liquidity, particularly for less-liquid off-the-run Treasury securities. This program allows primary dealers to sell these securities back to the Treasury regularly, aiming to alleviate balance sheet pressures and improve secondary market liquidity.

Empirical analysis, conducted by Jing Zhou using a difference-in-differences (DID) framework and instrumental variables (IV) to address selection bias, revealed that listing securities for buyback significantly narrows bid-ask spreads (up to 0.4 basis points) and raises prices (up to 19 cents per dollar). These effects are more pronounced for short-maturity securities and when dealers hold larger inventories. The purchasing effect, though statistically insignificant, also contributes to price increases. Both effects are localized, with aggregate liquidity gains being modest.

A theoretical model incorporating convex inventory costs and stochastic investor flows rationalizes these findings, showing that buybacks reduce dealers' liquidity risk through predictable demand, narrowing spreads and boosting prices, with effects persisting over time.

At the aggregate level, buybacks impact primary dealers' Treasury holdings, reducing coupon and bill positions, though impacts vary by secu

ORIZED

• 核心目标与机制：美国财政部于2024年5月推出流动性支持回购计划，旨在通过定期、可预测的方式让主 dealer 回购流动性较差的离市场证券，以缓解其资产负债表压力并提升二级市场流动性。

• 实证方法：研究使用 DID 框架分析成交前后的流动性变化，通过工具变量法解决选择偏差问题。数据显示，回购计划适度缩小了买卖价差，提高了回购证券的价格，并在库存较高时效果更为明显。

• 主要发现：

  1. 列入效应：回购证券的买卖价差缩小约0.4个基点，价格上升约0.19美元/美元，说明列入回购计划提高了流动性。
  2. 回购效应：实际回购后价格进一步上涨，但价差影响有限，说明真实回购使库存减少，从而提升了价格。
  3. 影响因素：短期证券和库存高的 dealer 回购效果更显著，回购对流动性的影响在短期内持久，但整体规模较小。

• 理论模型：流動支持規计划减少了 主 dealer 的库存风险，通过可预测的需求注入降低流动性风险，从而解释了回购对询价价差和价格的影响机制。

• 结论：回购计划成功提升了流动性，尽管规模有限，但可作为应对市场危机的辅助工具。改进回购频率和库存管理或有助于增加影响力度。

此摘要结合数据与理论，展示了回购计划对市场流动性的作用，强调了其在危机前的关键角色。