Netflix, the first-mover in the Over-the-Top(OTT) streaming business, has maintained its business leadership in terms of subscriber numbers despite the large and technological late entrants, such as Disney+, Amazon Prime Video, and Apple TV+. However, our understanding of Netflix’s content strategy seems limited from the perspective of content production and distribution rights. Thus, we aim to fill the research gap and address the following research question: “What is Netflix's content strategy, and how does it lead to its leadership?” Based on the movie and TV show level analysis, we found that Netflix mainly implemented a ‘Vertical Quasi-Integration(QI)’ strategy, focusing on exclusive streaming rights on content mainly produced by independent firms. We observed the effectiveness of the ‘Vertical Quasi-Integration (QI)’ strategy in terms of the weight of production costs, watching revenue, and profitability of total contents. We also recognized that the QI strategy seems appropriate considering the characteristics of OTT business, such as uncertainty of subscriber demand, asset specificity of content, and personalized content. Furthermore, we observed that Netflix developed three capabilities to implement the QI strategy, including (1) bargaining power consisting of six components, (2) mutual trust, and (3) Data analytics capabilities. Our findings provide relevant evidence on the leading firm strategy in OTT business and expand the understanding of QI strategy to new and emerging service industries.