Portfolio diversification is as important to debt management as it is to asset management. In this paper, we focus on diversification of sovereign debt issuance by examining the extension of the maximum maturity of issued debt. In particular, we are interested in the potential costs to the U.S. Treasury of introducing 50-year bonds as a financing option. Therefore, we first examine international evidence from four developed foreign government bond markets with such long-term debt. The results show that 50-year bonds in these markets trade at an average yield that is at most 20 basis points above that of 30-year bonds. Results based on extrapolations from a dynamic yield curve model using just U.S. Treasury yields are similar.

投资组合多元化对于债务管理和资产管理同样重要。在本文中，我们通过考察已发行债务最长期限的延长来关注主权债务发行的多元化。我们特别感兴趣的是美国财政部引入 50 年期债券作为融资选择的潜在成本。因此，我们首先研究来自四个发达外国政府债券市场的此类长期债务的国际证据。结果显示，这些市场上 50 年期债券的平均收益率比 30 年期债券高出最多 20 个基点。仅使用美国国债收益率的动态收益率曲线模型推断的结果是相似的。