Will Trump's Final Tariff Decision Announcement Impact ASEAN Stock Markets?

Abstract

Abstract - This study analyzes the impact of Trump's final tariff decision on the stock markets of six ASEAN countries (Indonesia, Thailand, Singapore, Malaysia, the Philippines, and Vietnam). Using an event study method, this research measures abnormal returns (AR) from the stock index over the five days preceding and following the announcement on July 8, 2025. The results show that only Indonesia and Thailand experienced statistically significant changes. Indonesia recorded a decline followed by a recovery after a trade agreement with the U.S., while Thailand successfully reduced import tariffs, supporting economic stability. In contrast, Singapore, Malaysia, the Philippines, and Vietnam did not show significant market responses. These findings indicate that while some ASEAN countries are sensitive to global trade policies, others are less responsive, highlighting the varying impacts of global economic policies in the region. This study contributes to understanding how ASEAN markets integrate new information, supporting the efficient market hypothesis, particularly in its semi-strong form.

Keywords – Trump’s Tariffs, ASEAN, Market Reactions, abnormal return, event study