Proceeding National Conference Business, Management, and Accounting (NCBMA)
9th National Conference Business, Management, and Accounting

CONFUSING BRAINS WITH RETURNS: EVIDENCE OF INVESTOR OVERCONFIDENCE AND TRADING ACTIVITY IN THE INDONESIAN STOCK MARKET

Yanuar Dananjaya (Universitas Pelita Harapan)
Hananiel Menoverdi (Universitas Pelita Harapan)
Priskila Napitupulu (Universitas Pelita Harapan)



Article Info

Publish Date
09 Jun 2026

Abstract

This study investigates the presence of investor overconfidence in the Indonesian equity market by analyzing the lead-lag relationship between stock returns and subsequent trading activity. Focusing on the constituents of the LQ45 index from January 2023 to December 2025, we employ a firm-level panel data approach with fixed effects and clustered robust standard errors on a monthly dataset (N=1,485$). Using share turnover as a proxy for trading intensity, the analysis tests the hypothesis that past positive returns lead to increased trading volume due to biased self-attribution. The empirical results demonstrate that both contemporaneous and lagged individual stock returns exert a positive and statistically significant influence on trading activity (p < 0.05$), confirming that Indonesian investors tend to trade more aggressively following periods of capital gains. This behavioral pattern remains robust across alternative turnover specifications, including total-share and free-float-based proxies, as well as log-transformed models. Furthermore, lagged market returns exhibit a dominant positive effect, suggesting that market-wide sentiment acts as a powerful catalyst for trading frequency. These findings provide strong evidence of overconfidence-driven behavior in the Jakarta Composite Index, highlighting how psychological biases—rather than purely fundamental information—drive market liquidity and volatility in an emerging market context.

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Journal Info

Abbrev

NCBMA

Publisher

Subject

Economics, Econometrics & Finance Social Sciences

Description

Prosiding National Conference Business, Management, and Accounting (NCBMA) berisi artikel-artikel ilmiah dari para peneliti secara nasional yang mengikuti konferensi NCBMA yang diadakan rutin setiap tahun oleh Fakultas Ekonomi dan Bisnis Universitas Pelita Harapan. Prosiding National Conference ...