<![CDATA[The K-pop phenomenon in Indonesia has given rise to a unique consumption pattern, namely the impulsive purchase of official merchandise by fans with high emotional involvement. This study aims to analyze the mechanism of impulse buying among fans of the K-pop boy group NCT (known as NCTzen) in Indonesia by examining the role of FOMO as a mediator between perceived scarcity and impulse buying, as well as the Bandwagon Effect as a moderator, within the Stimulus-Organism-Response (S-O-R) framework. This quantitative study used data from 236 respondents who were active NCT fans, obtained through purposive and snowball sampling, and analyzed using PLS-SEM. The results show that perceived scarcity has a significant effect on FOMO, and FOMO significantly drives impulse buying, whereas the direct effect of scarcity on impulse buying is not significant, confirming FOMO as a full mediator. The Bandwagon Effect is shown to strengthen the effect of scarcity on impulse buying. These findings indicate that product scarcity effectively drives impulse buying when it arouses social anxiety about being left behind, rather than merely conveying information about limited stock, with FOMO as the most dominant psychological factor. This study enriches the S-O-R framework within the context of digital fandom and offers practical implications for K-pop merchandise marketers, who can combine scarcity cues with social elements that trigger FOMO and the visibility of the community's collective behavior.]]>
