This study analyzed the disclosure effect among companies listed on the KOSPI market and the KOSDAQ market from 2007 to 2018 in which blockholders sold or bought their shares more than 5% of the company. In order to achieve the research objectives, the blockholders were categorized into ‘shareholder of more than 10% shares’, ‘de facto controlling shareholder’ and etc. There is a differentiation from the previous studies in that this study deals with both selling and buying of shares and only the change of more than 5% shares of the company. The main analysis results are as follows: First, in the short-term disclosure effect of the change in the blockholders’ equity, the sale of the blockholders’ equity had a negative effect and the purchase of the blockholders’ equity had a positive effect. As a result of analysis by types of blockholders, the sale by ‘shareholder of more than 10% shares’ and ‘de facto controlling shareholder’ all showed negative effects. In the case of purchase, the purchase by ‘shareholder of more than 10% shares’ showed a positive disclosure effect and the purchase by ‘de facto controlling shareholder’ showed a mixed result with positive and negative effects. Second, the long-term disclosure effect of blockholder's equity change showed a negative effect in both cases of selling and buying. ‘Shareholder of more than 10% shares’ and ‘de facto controlling shareholder’ also showed a negative effects. Third, in the short-term disclosure effect of blockholders' equity change, the disclosure effect was not significant for the sale of the executive blockholder, but the disclosure effect was significantly negative for the sale of the non-executive blockholder. On the contrary, the disclosure effect of equity selling was negative for executive blockholders and positive for non-executive blockholders. Fourth, as a result of the cross-sectional regression analysis, the share of blockholders had a significant positive effect on the cumulative excess return in the case of selling, but in the case of buying, there was no significant result. As a result of using the independent variable as the ratio of equity change, it was found that when the sale or purchase of the shares was large, the cumulative excess return is higher, but the cumulative excess return is lower in the purchase of shares more than 25%. This study analyzed the equity changes by various shareholder types, such as blockholders, executives, and executive blockholders unlike previous studies and there is a discrimination point in analyzing both selling and buying. In addition, it is significant that the blockholders were divided into ‘Shareholder of more than 10% shares’ and ‘de facto controlling shareholder’ to present economic implications. The results of the market reaction suggest that both the convergence of interest and the management entrenchment hypothesis hold for the blockholder's equity changes.