行业资产的Black-Litterman模型配置研究——基于社交网络情绪文本挖掘算法

研究目标:构建反映行业股价走势的基于社交网络文本挖掘算法的行业投资者情绪指标，并改善嵌入行业投资者情绪指标的Black-Litterman模型对资产的配置结果。研究方法:基于社交网络文本挖掘算法度量投资者情绪，运用主成分分析法构建行业投资者情绪指标，并嵌入Black-Litterman模型中构建投资者观点矩阵，确定行业资产配置比。研究发现:基于行业投资者情绪的BL模型有效提高了资产配置的日均收益率和夏普比率。实证结果在样本外验证(除受新冠疫情影响阶段)、暴涨暴跌阶段以及经过允许卖空和交易成本调整后仍稳健，进而证实了投资者情绪对资产组合有显著影响。研究创新:基于社交网络文本挖掘算法构建投资者情绪指数，解决了仅依赖于预期收益或历史数据的预测模型无法直观揭示投资者心理认知和行为的局限性问题，从一个崭新的视角科学地解决Black-Litterman模型中投资者观点的生成问题。研究价值:扩展了Black-Litterman模型理论体系研究，并推动了行为金融理论在资产配置中的应用。     

Forecasting aggregate stock market volatility with industry volatilities: The role of spillover index

In this paper, we aim to improve the predictability of aggregate stock market volatility with industry volatilities. The empirical results show that individual industry volatilities can provide useful predictive information, while the predictive contribution is limited. We further consider the spillover index between industry volatilities and find it displays strong predictive power for stock market volatility. Based on the portfolio exercise, we find that a mean-variance investor can achieve sizeable economic gains by using volatility forecasts of the spillover index. In addition, we conduct three extended analyses and further demonstrate the superior performance of the spillover index. Also, our results show robustness to a series of alternative settings. Finally, we investigate why the spillover index performs better and answer what information it contains. The results show that the spillover index can reflect and explain investor sentiments that are related to stock market volatility.     

Does investor sentiment affect fund crashes? Evidence from Chinese open-end funds

This paper aims to detect the impact of investor sentiment on the open-end fund crashes, drawing on the open-end stock funds and partial stock funds of China for the 2009–2019 period. The results show that the rise of investor sentiment will significantly increase the risk of the open-end fund crashes, which remains valid after robustness tests. Further researches indicate that the market timing and stock selection abilities of fund managers weaken the positive impact of investor sentiment on the open-end fund crashes, and the market illiquidity promotes the positive impact of investor sentiment on the open-end fund crashes.     

Pandemic-driven financial contagion and investor behavior: Evidence from the COVID-19

This paper studies the pandemic-driven financial contagion during the COVID-19 period and the impact of investor behavior on it by constructing three types of direct behavior measurements based on Google search volumes. More specifically, using a sample of 26 major stock markets around the world during the COVID-19 pandemic, we construct a non-linear financial contagion network via a dynamic mixture copula-EVT (extreme value theory) model to quantitatively detect and measure the complex nature of pandemic-driven financial contagion. Furthermore, through constructing direct investor behavior measurements including investor attention, sentiment, and fear, we find investor behavior plays an important role in explaining pandemic-driven financial contagion. We also find that the impacts of investor behavior on the pandemic-driven financial contagion are heterogeneous under several different settings, including market conditions, market development levels, regional subsets, and contagion directions.     

When does attention matter? The effect of investor attention on stock market volatility around news releases

We empirically investigate how retail and institutional investor attention is related to the way stock markets process information. With a focus on 360 US stocks in the S&P 500 universe, our results show that higher retail investors’ attention around news releases increases the post-announcement stock return volatility, whereas institutional investor attention has a small but negative impact on volatility on days following news releases on average over the cross-section of companies. These findings are in line with the hypotheses that attention of retail investors slows price-adjustments to new information and attention of institutional investors results in the opposite reaction. We show that these effects are heterogeneous in the type of news and the topic of the information being released. A portfolio allocation application highlights that these results are not only statistically significant but also sizeable in economic terms and can lead to an overperformance as large as dozens of basis points.     

险资入市促进了公司创新吗

随着国家政策的放开,保险公司持股上市企业的现象剧增,保险机构投资者逐渐成为中国资本市场中的重要角色,对企业经营决策发挥了重大作用。在此背景下,本文考察了险资入市对企业创新活动的影响。研究发现:一方面,保险机构投资者持股公司的研发投入和专利产出更少;另一方面,保险机构投资者持股公司的CEO强制变更概率更高,经营业绩更差。本文还讨论了保险公司影响企业创新背后的理论机理。本文研究表明,险资持股带来了过度监督效应,抑制了企业创新。本文有助于市场加深对保险机构的认识,丰富企业创新的相关研究,为改善公司治理提供建议。保险机构投资者是中国资本市场改革的重要力量,政府监管部门需合理引导保险机构投资者,使其发挥积极的外部治理作用。