中金：指数调整效应未来如何演变？

Core Viewpoint - The article emphasizes the significance of predicting the adjustment lists of A-share indices in advance, which can provide substantial benefits for various investors, including arbitrage and cross-border investors [1][2]. Group 1: Index Adjustment Predictions - A-share indices undergo regular adjustments in June and December each year, allowing for predictions based on trading and financial data from the previous year [1][5]. - The report predicts the adjustment lists for several indices, including CSI 300, CSI 500, and others, for June 2025 based on component stock selection rules [1][5]. Group 2: Impact of Passive Fund Growth - The rapid increase in passive fund sizes since 2023 has enhanced the significance of index adjustment effects, particularly for indices like CSI 300 and STAR 50 [2][8]. - The average excess returns for newly included stocks in various indices have improved post-announcement, with CSI 300 and SSE 50 showing increases to 4.64% and 6.77% respectively in the 10 days following the announcement [2][12]. Group 3: Factors Influencing Adjustment Effects - The decline in the significance of index adjustment effects in overseas indices post-2010 is attributed to factors such as sample size, index migration, and liquidity [3][51]. - In A-shares, index migration and pre-announcement trading behaviors negatively impact the inclusion effects, while high impact coefficients positively influence them [3][51]. Group 4: Future Excess Return Potential - The current trends indicate that the future A-share market may still have excess return potential from index adjustment events, as key indicators like circulation market value and impact coefficients show no downward trend [4][51]. - High impact coefficient strategies have demonstrated strong performance, achieving annualized returns of around 10% from 2019 to 2024 [4][56]. Group 5: Strategy Development - The strategy of predicting index inclusion samples in advance has shown significant enhancement in returns, with annualized returns increasing from 2.5% to 5.7% when holding positions before announcements [52][56]. - A strategy focusing on high impact coefficient stocks has yielded an annualized return of 8.1% since 2010, outperforming the CSI 300 index by 7.2% during the same period [56].