The recent financial and sovereign debt crises showed that providing public guarantees to banks may pose serious threats to sovereign solvency, despite their short-term beneficial effects on financial stability. This article analyses the role that public guarantees to banks play in the bank-sovereign nexus and offers a more nuanced assessment of their implications for sovereign debt crises. Depending on the nature of the banking crisis and the specific characteristics of the economy, guarantees may improve financial stability without undermining sovereign solvency, thus generating a positive feedback loop between bank and sovereign stability.