Public debt management

Abstract: This thesis consists of three self-contained papers covering different aspects of public debt management. From a methodological point of view they all have in common that results and models from the theory of finance are used to analyze the effects of public debt management.The first paper, Neutrality of Public Debt Management, studies the case when public debt management does not matter, i.e. when it is neutral. Although strong assumptions are needed to ensure neutrality of public debt management it is nevertheless of interest to study it, since an analysis illuminates the mechanisms through which public debt management affects the economy. The paper starts with a discussion of the assumptions that are needed to ensure neutrality in the models used in the literature. The remainder of the paper tries to relax some of these assumptions. The model employed is an intertemporal general equilibrium model. It is shown that if the agents are identical, public debt is neutral provided the agents pierce the veil of government, and all taxes associated with public debt are lump-sum. It is also shown that if the agents are different but have sufficiently similar utility functions that exhibit hyperbolic absolute risk aversion (i.e., the agents have linear risk tolerance), public debt management is neutral in aggregates, provided the agents pierce the veil of government and all taxes associated with the debt service are lump-sum. This means that public debt management neither affects prices nor aggregate consumption; it might, however affect the individual agent’s consumption-savings decision. Since the class of utility functions that exhibit hyperbolic absolute risk aversion is widely used in economic analysis, this result has several theoretical and empirical implications. The result also has implications for the choice of model in the third paper of the thesis.The second paper, Objectives of Public Debt Management, discusses the objectives of public debt management in an atemporal mean-variance framework. The model employed in this paper differs in one important aspect from the ones previously used in the literature; it takes the firms’ investment decisions into account and hence endogenizes the supply of assets to some extent. It is shown that if the firms’ behavior is introduced, objectives that in the literature have been assumed to stimulate the economic activity do not necessarily have the desired effect. The paper also discusses different objectives aiming at welfare-improvements and economic stimulation. Since the analysis is performed in a unified framework, it is possible to compare the objectives and to discuss their welfare implications. Of particular interest is the welfare aspects of minimization of the costs of public debt. Finally, the paper also discusses the effectiveness of the objectives and it is shown that with one exception, cost minimization, effectiveness declines when the government-issued debt instruments’ share of the asset market falls.The last paper, Public Debt Management and the Term Structure of Interest Rates, develops and uses a stochastic overlapping generations model to analyze the impact of public debt management on the term structure of interest rate. In most of the literature public debt management is thought of as changes in the maturity structure of the outstanding public debt. A change in the maturity structure implies that public debt management affects, e.g., future tax liabilities and hedging opportunities. To capture these effects it is necessary to use an intertemporal framework. In contrast to most models in the literature on public debt management, the model in this paper is intertemporal and takes the general equilibrium effects of public debt management into account, by integrating the financial and real sectors of the economy. This means that current and future asset prices, as well as investments are affected by public debt management. The analysis suggests that it is not the quantities of the long-term and short-term bonds, per se, that determine the effects on the term structure of interest rates. What determines these effects is how public debt management affects the hedging opportunities through changes in asset supply, taxes and prices.