Purpose The research examines the influence of fintech, broad money and population growth on bank stability (Z-score). We examined the unique interaction of fintech, broad money and population growth to assess the relevance and direction of their association with bank stability. Design/methodology/approach The study sample comprises seven ASEAN nations covering 2010–2022. We employed quantile regression models to identify the significance and directions of exogenous variables on the endogenous variable. Also, for robustness, we used the fixed effect method. Findings Fintech has a significant indirect impact on financial stability at almost all levels of quantiles. Broad money growth constantly demonstrates a significant negative influence on financial stability throughout most of the quantiles. Population growth exhibits a significant positive impact on financial stability at lower quantiles; however, it turns negative at higher quantiles. Finally, the interaction of fintech, broad money growth and population growth is positive and significant across all quantiles. Research limitations/implications The study highlights the essential need to regulate broad money expansion, manage fintech adoption and synchronise population growth to mitigate the possible risks of beyond appropriate thresholds in ASEAN’s financial institutions and ensure financial stability. Ensuring structural resilience and promoting sustainable development requires a systematic and precisely calibrated approach. Originality/value This study offers a new examination of the intricate relationship of fintech adoption, overall money growth and demographic factors in influencing bank stability. Examining their collective impacts provides sophisticated insights into the structural factors affecting financial stability in developing ASEAN economies.