NISA 對日本股市流動性之影響

Abstract

這研究利用東証股價指數（TOPIX）成分股的縱橫資料，從短期、中期與長期的視角出發，定量分析了免稅投資計劃一般NISA（2014年推出）與積立NISA（2018年推出）對日本股市的交易量、交易價值、周轉率及流動性的影響。研究結果顯示，一般NISA在中期內顯著提升了市場活化，但其長期影響較為有限。相較之下，積立NISA在長期內皆有助於市場的穩健活化，然而在中期階段則出現了一定程度的暫時性下降。這些發現表示，NISA在促進家庭資產流入投資方面發揮了一定作用，但若要持續推動長期市場活化，仍需配合額外的政策措施。

This study quantitatively analyzes the impact of tax-exempt investment scheme: the General NISA (introduced in 2014) and the Tsumitate NISA (introduced in 2018) on trading volume, trading value, turnover and liquidity in the Japanese stock market, using panel data of TOPIX constituent stocks. The analysis is conducted from short-term, medium-term, and long-term perspectives to capture the temporal evolution of these impacts. The findings indicate that while the General NISA significantly improved liquidity indicators in the medium-term, its long-term effects remained limited. In contrast, the Tsumitate NISA contributed to a gradual market revitalization in the long-term, although a temporary decline was observed. These insights suggest that the NISAs have been moderately effective in directing household assets toward investment. However, they also imply that additional policy measures are necessary to sustain long-term market revitalization.