Journal of International Conference Proceedings
Vol 8, No 4 (2025): 2025 ICPM Hong Kong

Analysis Of Abnormal Stock Returns One Week After The First Confirmed Covid-19 Case in Indonesia

Ariantara, Made Arvin (Unknown)
Oktayanti, Ni Putu Riza (Unknown)
Astawa, I Made (Unknown)
Manuaba, I Gede Made Bagus Wira (Unknown)
Ariestiani, Ni Wayan (Unknown)
Widiadana, Kadek Alexs Padma (Unknown)



Article Info

Publish Date
17 Jan 2026

Abstract

This study examines the reaction of the Indonesian capital market to the announcement of the first confirmed COVID-19 case in Indonesia on March 2, 2020, by applying an event study approach to stocks included in the IDX SRI-KEHATI index. The sample consists of 25 companies, with an observation window of 11 trading days (t?5 to t+5) and an estimation period of 60 days. Abnormal returns were calculated using the market model to identify short-term market reactions to unexpected public information. The results indicate that the majority of stocks experienced negative abnormal returns around the event date, reflecting heightened investor uncertainty. On the announcement day (t?), several major stocks recorded significant negative abnormal returns, such as BBRI (?0.03361), BBNI (?0.03042), BTPS (?0.04307), and a negative accumulated abnormal return (ARTN) of ?0.02313. Although a limited number of stocks, including ASII (0.05942) and ANTM (0.03915), showed positive abnormal returns, the overall average abnormal return (AAR) declined sharply after the event. The cumulative average abnormal return (CAAR) continued to decrease throughout the post-event period, indicating a sustained negative market response. These findings support the semi-strong form of the Efficient Market Hypothesis, suggesting that the Indonesian capital market reacts quickly but unevenly to systemic crisis information

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Journal Info

Abbrev

JICP

Publisher

Subject

Humanities Decision Sciences, Operations Research & Management Electrical & Electronics Engineering Industrial & Manufacturing Engineering Languange, Linguistic, Communication & Media

Description

JICP is proceedings series that aims to publish proceedings from conferences, in the fields of economics, business, and management research. All proceedings in this website are open access, which means the published articles are permanently free to read, download, copy, and distribute. The online ...