PUBLIC DEBT UNDER LIMITED PRIVATE CREDIT
研究了当私人借贷受限时，政府能否用公共债务替代私人信贷。发现高公共债务政策虽能完全放松借贷限制，但并非最优，因为它会减少投资者对短期资产的配置，从而降低应对流动性冲击的能力。
There is a conventional wisdom in economics that public debt can serve as a substitute for private credit if private borrowing is limited. The purpose of this paper is to show that, while a government could in principle use such a policy to fully relax borrowing limits, this is not generally optimal. In our economy, agents invest in a short-term asset, a long-term asset, and government bonds. Agents are subject to idiosyncratic liquidity shocks prior to the maturity of the long-term asset. We show that a high public debt policy fully relaxes private borrowing limits and is suboptimal. This is because agents expecting such a policy respond by investing less than is socially optimal in the short asset which can protect them in the event of a liquidity shock. The optimal policy is more constrained and it induces a wedge between the technological rate of return on the long asset and the rate of return on bonds. In such a regime, agents subject to liquidity shocks are also borrowing constrained, and this expectation of being borrowing constrained induces them to invest the optimal level in the short asset.