This paper investigates the trends, cycles, and irregular components in the international reserves of three South Asian  Association for Regional Cooperation (SAARC) members: Bangladesh, India, and Pakistan. These countries were chosen because their economies, remittances, FDI, exports, and foreign investment are all growing fast. In this paper, the international reserve of each nation is decomposed using the unobserved components model, and the relationship between each component and these countries is investigated. The years 1971–2021 have been selected as the time frame for the research, and the statistical dataset used as World Bank Development website has been examined. The model is estimated using a maximum likelihood approach and the smooth trend plus stochastic cycle method developed by Koopman et al. (2009). The model will primarily be evaluated by the residual diagnostics, which will show that it has a good fit. In addition, the diagnostics of normality, auxiliary, prediction, and forecast all point to the fact that there is not a defect in the model. In perspective of irregular components, empirical research shows clearly that Pakistan has a positive correlation with India but a strong negative correlation with Bangladesh. Lastly, a stronger correlation can be found between the three countries during shorter cycles than longer cycles.