The rapid growth of mobile banking (m-banking) has led to a surge in its popularity as a convenient and accessible way to conduct financial transactions. However, despite its benefits for both banks (reduced operating costs, expanded services, improved quality) and customers (convenience, accessibility, prompt information), m-banking adoption rates have not met expectations. Existing research on m-banking has focused primarily on initial adoption rather than continuance intention, with limited work on user adaptation and the moderating role of trust. This study addresses these gaps by exploring the determinants of user behavioral adaptation and continuance intention toward m-banking, and examining the moderating influence of trust on the relationships between adaptation/satisfaction and continuance intention. The study's significance lies in its examination of the Vietnamese m-banking context, a rapidly growing market with significant potential, where such research is scarce. The research questions are: (1) What are the determinants of user behavioral adaptation and continuance intention in m-banking? (2) How do these determinants affect adaptation and lead to continuance intention? (3) How does user trust moderate the impact of adaptation and satisfaction on continuance intention?

The literature review explores the evolution of m-banking, distinguishing it from internet banking, and highlighting its benefits for both banks and customers. It reviews various models used to study m-banking adoption and usage, including the Technology Acceptance Model (TAM), Expectation-Confirmation Theory (ECT), the Expectation-Confirmation Model (ECM), and the Unified Theory of Acceptance and Use of Technology (UTAUT). The review points out the inconsistencies and mixed findings in the literature, emphasizing the need for a more comprehensive model. It introduces the Expectation-Confirmation Model (ECM) as the foundation for this study due to its focus on post-adoption behavior and satisfaction. The review also integrates the Decomposed Theory of Planned Behavior (DTPB) to account for the multi-dimensional aspects of attitudes, subjective norms, and perceived behavioral control, and the Adaptive Structuration Theory for Individuals (ASTI) to understand the dynamic interaction between users and the technology. Finally, the review considers the crucial role of trust in influencing m-banking usage.

The study employed a questionnaire-based survey using convenience and snowball sampling methods among 523 mobile banking customers in three major Vietnamese cities (Hanoi, Ho Chi Minh City, and Da Nang). The participants were customers of Vietcombank, Vietinbank, and Techcombank, three of Vietnam's largest banks. A pre-test was conducted to refine the questionnaire items, ensuring clarity and understandability. The survey consisted of three sections: screening questions, a set of 30 items measuring the study constructs, and demographic questions. Data was collected through face-to-face interviews and online responses. The collected data was analyzed using partial least squares structural equation modeling (PLS-SEM) with SmartPLS 4.0 software. The authors used Harman's single-factor test to assess common method variance (CMV) bias and found that CMB was not a significant concern. Collinearity analysis using the Variance Inflation Factor (VIF) also confirmed the absence of multicollinearity issues. The outer model was evaluated for reliability (Cronbach's alpha, composite reliability, AVE) and validity (discriminant validity using HTMT), ensuring the quality of the measurement model. The inner model was then evaluated using bootstrapping to assess the significance of path coefficients, R-squared, and predictive power using PLSpredict. The moderating effect of trust was assessed using interaction terms in the model. The sample size of 523 exceeded the recommended minimum for PLS-SEM analysis.

The results of the PLS-SEM analysis revealed that perceived usefulness, satisfaction, adaptation, and self-efficacy significantly and positively influenced continuance intention toward m-banking. Subjective norm, however, did not show a significant relationship with continuance intention. The R-squared values for continuance intention (CI), adaptation (ADP), and satisfaction (SA) were 0.243, 0.096, and 0.222, respectively, indicating a moderate level of explanatory power. The study found strong support for the hypotheses linking satisfaction, perceived usefulness, confirmation, and adaptation to continuance intention. Self-efficacy also significantly influenced continuance intention. The analysis of the moderating effect of trust revealed that it significantly moderated the relationship between adaptation and continuance intention. Higher levels of trust strengthened the positive relationship between adaptation and continuance intention. In contrast, trust did not significantly moderate the relationship between satisfaction and continuance intention.

The findings provide strong evidence supporting the extended expectation-confirmation model for predicting continuance intention in mobile banking. The significant role of adaptation highlights the importance of user-friendly interfaces and functionalities in promoting continued usage. The positive relationship between perceived usefulness, satisfaction, and continuance intention confirms the importance of providing value and a positive user experience. The moderating role of trust underscores the need for banks to build trust with their customers to enhance the effectiveness of adaptation in driving continued mobile banking use. The lack of significant effect of subjective norm on continuance intention suggests that social influence may be less critical than personal experience and perceived usefulness in this context. The results contribute to the existing literature by integrating multiple theoretical frameworks and investigating the specific context of mobile banking in Vietnam.

This study makes several significant contributions. It integrates three theoretical frameworks (ECM, DTPB, and ASTI) to provide a novel model for predicting m-banking continuance intention. It sheds light on the crucial role of user adaptation and the moderating impact of trust on this relationship. The findings offer practical implications for banks in enhancing customer retention and fostering continued m-banking usage. Future research could extend this study to other cultural contexts, incorporate individual innovativeness as a variable, and explore the long-term effects of trust on m-banking continuance.

The study is limited by its focus on the Vietnamese context, potentially limiting the generalizability of the findings. The cross-sectional nature of the data limits the ability to establish causal relationships between variables. Future research should consider longitudinal studies to investigate the dynamic interplay between the variables over time. The study could also be expanded to include other relevant factors, such as perceived risk, privacy concerns, and individual differences in technology adoption.