Impact of Indonesia’s Financial Minister Reshuffle on Market Sentiment: A Market Reaction of the Jakarta Composite Index (IHSG)

Abstract

This research looks on how the Indonesian stock market responded to the sudden announcement of the Minister of Finance reshuffle on September 8, 2025. By observing the Jakarta Composite Index (IHSG) within a 21-day window (t-10 to t+10), we sought to determine if such high-level political shifts trigger significant investor movement. Given the severe data limitations encountered during the cleaning process (N=10), this study specifically adopted  the Zero-Return Model to estimate expected returns. Our descriptive findings point to a positive trend, with an Average Abnormal Return (AAR) of +0.37% and a Cumulative Abnormal Return (CAR) reaching +3.69%. Despite this upward trajectory, the One-Sample t-Test resulted in a P-value of 0.2466, confirming that the reaction was not statistically significant. This suggests that the Indonesian market functions under the Semi-Strong Form of the Efficient Market Hypothesis (EMH), where information is likely absorbed through an anticipation effect before the official announcement