买了指数基金就不用分散投资吗？

Core Viewpoint - The article discusses the performance differences among various index funds, particularly focusing on the volatility and returns of large-cap and small-cap indices over the past decade, highlighting the challenges in choosing the best investment strategy among them [3][5][24]. Performance Analysis of Different Indices - Historical data shows significant performance disparities among indices of different sizes over the past ten years, with the 中证2000 exhibiting the highest volatility and returns during bullish phases, while the 沪深300 remains relatively stable [5][7]. - The 中证全指 demonstrates a balanced performance, generally staying within a moderate range with fewer extreme fluctuations compared to other indices [5][7]. Bull Market Performance - In 2014, all five indices saw substantial gains, with 沪深300 and 中证2000 both around 50%, while 中证全指, 中证500, and 中证1000 had returns between 30%-45% [10]. - The year 2015 marked extreme differentiation, with 中证2000 soaring over 100%, while 沪深300 showed minimal growth [11]. - In 2019, all indices rose moderately, with gains concentrated in the 20%-35% range, favoring 沪深300 and 中证全指 slightly [12]. - The year 2020 saw a general tightening of gains, with most indices recording increases between 10%-20%, and 沪深300 slightly outperforming small-cap indices [13]. Bear Market Performance - During bear markets, indices generally experienced significant declines, with the depth of the drop closely related to market capitalization structure [17]. - In 2016, the 中证全指 and 沪深300 fell by 5%-8%, while 中证500 and 中证1000 dropped by 10%-15%, and 中证2000 remained relatively stable [17]. - The year 2018 witnessed a severe downturn, with 中证1000 and 中证2000 suffering losses of nearly 40% and over 35%, respectively, while large-cap indices also faced declines exceeding 25% [18]. - In 2022, all indices recorded declines in the 15%-25% range, with small-cap indices and 中证全指 experiencing slightly larger drops, while 沪深300 fared better [19]. - In 2023, most indices recorded slight declines or remained flat, with only 中证2000 achieving approximately 2% positive returns, indicating that small-cap indices often bear greater adjustment pressure in bear markets [20]. Summary of Returns and Volatility - 中证2000 has the highest cumulative return at nearly 197% with an annualized return of 10.19% and a volatility of 28.26%, indicating high elasticity and risk [23]. - 中证全指 and 沪深300 show long-term returns of 84.46% and 79.11%, respectively, with annualized returns in the 5%-6% range and lower volatility, reflecting stability and balanced returns [23]. - 中证500 and 中证1000 fall in between, with cumulative returns of 67.92% and 55.63%, annualized returns slightly below 5%, and volatility ranging from 21%-27% [23]. Investment Strategy Recommendations - The article suggests that small-cap indices perform better during favorable market conditions but come with higher volatility and drawdown risks, while large-cap and broad-based indices offer more stable returns [24]. - A diversified investment approach, such as balancing large-cap and small-cap allocations and integrating growth and value styles, is recommended to enhance adaptability across different market conditions [24].