Traditionally, the private wealth management industry has been dedicated to high-net-worth individuals due to expensive service costs. However, robo-advisors are making sudden rises during the on-going FinTech revolution. Robo-advisors aim to provide personalized wealth management services for everyone by using automated investment management algorithms and online distribution channels. To reduce service costs, robo-advisors mainly use ETFs to construct investment portfolios. Therefore, Korean ETF market should grow in both quantity and quality, in order for robo-advisors to succeed in Korea. In this study, we first analyze how vulnerable the Korean ETF market is to external or internal shocks in comparison with the U.S. ETF market. Then, we derive the optimal introduction sequence of ETFs in the Korean ETF market based on the modern portfolio theory.