While the global financial crisis in 2008 followed by stricter financial regulations cowered activities of traditional big financial institutions, new venture start-ups armed with information communication technologies had begun entering into financial sectors. These start-ups have gone beyond mere application of ITs into financial services and have become new players or competitors through previously unavailable convergence-based innovations in financial markets. Some prominent overseas Fintech start-ups are offering new financial services for customers through convergence of existing functions in finance industry, or through convergence of industries between finance and non-finance areas, or through involving end-customers in their financial service rendering process. However, it is voiced out that emergence of innovative Fintech startups in financial market in S. Korea largely hindered by strict government regulations which is fundamentally positive style, unlike the negative style regulatory system in other major countries such as US. Regulations in general limit the choice of stake-holders and impose responsibilities on them but at the same time they are necessary in order to protect and increase public welfares. Especially, because of its magnitude of impact on national economy, finance industry is in general subject to stronger and broader government regulations. In specific, the industry is subject to regulations on financial service per se, on information protection, and is also exposed to shadow regulations such as administrative guidelines set by government agencies. As a result, if these regulations are not accommodating advances in technologies and firms’ innovativeness, then ambitious challenges of Fintech start-ups will be subjecting to violation of regulations and could not even be considered to introduce in marketplaces. The purpose of this paper is to introduce the convergence-based innovation through the case studies of successful Fintech start-ups in oversea market and to understand the effects of domestic financial regulations and the market participants' conflict of interest on successful implementation of the innovations in S. Korea. For this purpose, this study describes in detail, among the prospect start-ups chosen three times by Forbes from 2015 to 2018, nine overseas Fintech start-ups that provide innovative value through the convergence-based innovation. And we discuss the effects of regulations regarding financial services, information protection, and shadow regulations on those innovations in more detail assuming that these businesses will enter S. Korea's financial market.