NATIONAL BUREAU OF ECONOMIC RESEARCH
NATIONAL BUREAU OF ECONOMIC RESEARCH

A New Index of Debt Sustainability

Olivier J. Blanchard, Mitali Das

NBER Working Paper No. 24068
Issued in November 2017
NBER Program(s):International Finance and Macroeconomics

Debt sustainability is fundamentally a probabilistic concept: Debt is rarely sustainable with probability one. We propose an index of external debt sustainability that reflects this uncertainty. Namely we construct the index as the probability that, at the current exchange rate, net external debt is equal to or less than the present value of net exports. Constructing this index involves three steps: (1) deriving the distribution of the present value of net exports at the current exchange rate; (2) deriving the distribution of exchange rates associated with the condition that, for each realization, the present discounted value of net exports is at least equal to the value of current net debt; and (3) assessing where the current exchange rate stands in the distribution of exchange rates and thus the probability that debt is sustainable. Having shown how this can be done, we then compute the index for two countries, the United States and Chile. Our main conclusion is the large degree of uncertainty implied by the presence of large gross asset and liability positions, together with uncertainty about rates of return on these assets and liabilities. The size of the distribution of exchange rate adjustments implies that one should be careful in concluding that debt is or is not sustainable at the current exchange rate and that strong measures are potentially needed to reestablish sustainability. Exchange rates that appear overvalued in the baseline may still imply a reasonably high probability that debt is sustainable at the current exchange rate; symmetrically, exchange rates that appear undervalued in the baseline may still come with a reasonably low probability that debt is unsustainable at the current exchange rate.

You may purchase this paper on-line in .pdf format from SSRN.com ($5) for electronic delivery.

Access to NBER Papers

You are eligible for a free download if you are a subscriber, a corporate associate of the NBER, a journalist, an employee of the U.S. federal government with a ".GOV" domain name, or a resident of nearly any developing country or transition economy.

If you usually get free papers at work/university but do not at home, you can either connect to your work VPN or proxy (if any) or elect to have a link to the paper emailed to your work email address below. The email address must be connected to a subscribing college, university, or other subscribing institution. Gmail and other free email addresses will not have access.

E-mail:

Supplementary materials for this paper:

Machine-readable bibliographic record - MARC, RIS, BibTeX

Document Object Identifier (DOI): 10.3386/w24068

 
Publications
Activities
Meetings
NBER Videos
Themes
Data
People
About

National Bureau of Economic Research, 1050 Massachusetts Ave., Cambridge, MA 02138; 617-868-3900; email: info@nber.org

Contact Us