Frontier markets offer investors the promise of higher growth. Of late, that has come in the form of debt, not earnings.

Financial conditions for emerging economies have tightened dramatically over the past six months, according to the IMF’s latest Global Financial Stability Report, published on Tuesday. The soaring dollar and rising interest rates threaten to push dozens of countries to the brink of sovereign default.

The smallest emerging markets, so-called frontier markets, have the worst of it. Many are in Africa and, like Ghana and Zambia, have only sold their first foreign bonds in the past decade or so. But even larger economies, such as Brazil and India, which have been more resilient against the multiple crises of the past two years, are not immune.