中文摘要：

股权分置改革完成后，随着大批限售股解禁，大小非减持已成为当前理论界和实务界共同面临的关键问题。文章在理论上首次通过动态模型研究大股东减持，结果发现控股股东最优减持与其现金流权及公司治理水平正相关，而与控制权私利、外部市场回报负相关，且减持并非其必然选择。同时，由于调整成本的存在，控股股东减持是一个持续的动态过程。基于第一大股东减持数据，实证研究结果基本验证了理论发现。文章揭示了大股东减持的内在机制，为股权分置改革后大股东持股结构调整提供了理论依据，同时也在一定程度上解释了当前市场上的减持现象。

英文摘要：

After the completion of stock circulation reform, the holding reduction of large-and-small-sized stocks with limited circulation becomes a key issue. In the theoretical perspective, the paper studies the issue about the holding reduction of large shareholders through dynamic models and finds that the optimal holding reduction of controlling shareholders is positively related with cash flow right and corporate governance level, but has negative effects on the private benefits of control right and external market returns. And holding reduction is not the inevitable choice. Meanwhile, owing to the adjustment cost, holding reduction of controlling shareholders is a constant and dynamic process. The empirical study verifies the theoretical prediction. By revealing the inherent mechanism for holding reduction of large shareholders, the paper provides theoretical support for the adjustment of large shareholders＇ holding structure after the stock circulation reform, and also explains the current holding reduction to some extent.