Abstract
The Vietnamese stock market is a dynamic emerging market that remains highly susceptible to crowd psychology. This study updates the empirical evidence by measuring and identifying the presence of herding behavior in the Vietnamese stock market over the period 2017-2025, while also comparing such behavior across the two listed exchanges, the Ho Chi Minh Stock Exchange (HOSE) and the Hanoi Stock Exchange (HNX). By applying the Cross-Sectional Absolute Deviation (CSAD) model, the results confirm the existence of herding behavior on both exchanges, with crowd psychology found to be stronger on HOSE than on HNX. These findings highlight the urgent need to enhance information transparency and improve market efficiency.