NBER Working Papers · 2026 · [{"name": "Wenhao Li", "affiliation": []}, {"name": "Sebastian Merkel", "affiliation": []}]
中文摘要
我们表明，量化宽松（QE）会恶化政府债务可持续性。在我们的模型中，政府的基本财政余额为负，且债务需求曲线向下倾斜，这使得利率内生化。中央银行持有长期资本，并将利润上缴财政当局。QE会耗尽这部分资本存量，减少未来的利润上缴和危机应对储备。与Sargent和Wallace（1981）的结论——更大程度的货币宽松会降低稳态债务水平——相反，我们表明QE会提高稳态债务水平，并将违约边界向内移动，从而加剧脆弱性、降低债务可持续性。此外，尽管QE可以在较长时期内维持低利率，但要维持由QE支撑的利率钉住，需要中央银行足迹不断扩大、资本加速耗尽，直至融资成本急剧上升。在某些参数条件下，大规模QE会使原本可持续的债务水平变得不可持续，最终导致主权违约。
Abstract
We show that quantitative easing (QE) worsens government debt sustainability. In our model, the government has a negative primary balance and downward-sloping debt demand that makes interest rates endogenous. The central bank has long-term capital and remits profits to the fiscal authority. QE depletes this capital stock, reducing future remittances and crisis-fighting reserves. Contrary to Sargent and Wallace (1981), where greater monetary accommodation lowers the steady-state debt level, we show that QE increases the steady-state level of debt and shifts the default boundary inward, thus heightening fragility and reducing debt sustainability. Moreover, while QE can keep interest rates low for extended periods, sustaining a QE-backed rate peg requires a growing central-bank footprint and accelerating capital depletion, until financing costs rise sharply. Under certain parameters, large-scale QE makes previously sustainable debt levels unsustainable, leading ultimately to sovereign default.