{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,31]],"date-time":"2025-10-31T21:41:04Z","timestamp":1761946864683,"version":"build-2065373602"},"reference-count":32,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2025,8,9]],"date-time":"2025-08-09T00:00:00Z","timestamp":1754697600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Systems"],"abstract":"<jats:p>The COVID-19 pandemic caused major disruptions to worldwide financial markets, which resulted in market instability and unpredictability. South Korean investors used sector-specific exchange-traded funds (ETFs) to handle the market challenges. This research examines the connection between COVID-19 statistics, including total confirmed cases and deaths, and Korean sector ETF market performance. The research uses the ARIMAX model to evaluate how external variables affect ETF price volatility. The research uses Granger causality tests to determine the direction of relationships between pandemic metrics and sectoral performance, while K-means clustering identifies patterns across different sectors. The analysis reveals significant statistical connections between pandemic disruptions and three sectors, including communication services, healthcare, and IT. The research shows that COVID-19 metrics strongly affected the performance of sector-specific ETFs throughout the analyzed time period. The research establishes a basis for additional studies about external shock effects on financial instruments and delivers valuable information to investors and policymakers who need to manage global crisis risks.<\/jats:p>","DOI":"10.3390\/systems13080678","type":"journal-article","created":{"date-parts":[[2025,8,11]],"date-time":"2025-08-11T09:59:13Z","timestamp":1754906353000},"page":"678","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Deciphering the Impact of COVID-19 on Korean Sector ETFs: Insights from an ARIMAX and Granger Causality"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2596-7368","authenticated-orcid":false,"given":"Insu","family":"Choi","sequence":"first","affiliation":[{"name":"Department of Industrial and Systems Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tae Kyoung","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Industrial and Management Systems Engineering, Kyung Hee University, Yong-in 17104, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sungsu","family":"Park","sequence":"additional","affiliation":[{"name":"Department of Industrial and Management Systems Engineering, Kyung Hee University, Yong-in 17104, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kyeong Soo","family":"Shin","sequence":"additional","affiliation":[{"name":"Department of Industrial and Management Systems Engineering, Kyung Hee University, Yong-in 17104, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Suin","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Industrial and Management Systems Engineering, Kyung Hee University, Yong-in 17104, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8385-9598","authenticated-orcid":false,"given":"Woo Chang","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Industrial and Systems Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,8,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"649","DOI":"10.1007\/s10690-021-09340-w","article-title":"Financial network connectedness and systemic risk during the COVID-19 pandemic","volume":"28","author":"So","year":"2021","journal-title":"Asia-Pac. 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