The purpose of this study is to examine the relationship between users' optimal experience while surfing SNS, the sharing behavior of fake news about companies, online trust, and increased social media usage. Our theoretical framework enhances flow theory, which is conceptualized as a sequential process, involving social media users' intrinsic interest, concentration, perceived control, enjoyment, and time distortion. Relevant studies from fake news literature, online trust, and social media usage were also included to develop the hypothesis and conceptual model. We (...) conducted an empirical investigation through a questionnaire-based online survey among social media users of the most popular SNS. A convenience sample was chosen, and 922 valid responses were obtained. Using structural equations modeling we tested the research hypothesis and the proposed conceptual model. The findings show that the optimal experience of social media users can be viewed as a sequential process that influences sharing fake news about companies: intrinsic interest influences concentration, concentration influences perceived control, perceived control influences enjoyment, enjoyment influences users time distortion, and time distortion influences sharing fake news about companies on SNS. Moreover, online trust has a positive influence on sharing fake news. Also, the results of this study indicate that sharing fake news about companies while browsing SNS has a positive influence on social media usage. The paper extends the theoretical understanding of the flow theory in the social media context of an emerging market. Marketers can benefit from the results of this study when designing communication strategies via social media, as to know what content to post, how to avoid the spread of fake news, and which aspects to consider enhancing optimal experience among SNS users. (shrink)