深度学习能否让失效因子“起死回生”？——基于Transformer模型的中国A股市场月频动量效应挖掘研究

本文使用基于Transformer模型的深度学习算法成功发现了中国A股市场的月频动量效应，并通过分析模型的信息挖掘机制解释了过去A股市场的“月频动量效应消失之谜”。具体而言本文证实Transformer模型能够利用高维嵌入算法与注意力机制成功甄别以彩票型股票偏好和非理性交易行为为代表的市场噪音，在去除相应的干扰因素后中国A股市场存在显著的月频动量效应，多空组合能够获得0.29%的平均月度收益。进一步地本文从行为金融的视角对A股市场动量效应的形成机制进行了相应分析，证实投资者对市场信息的反应不足是动量效应存在的重要原因。本文研究证实深度学习算法可以利用算力优势挖掘增量信息并增强传统因子的定价能力，对提升资本市场定价效率和投资实践具有一定的启示意义。     

我国沪市周内效应实证探究——基于修正EGARCH模型

股票市场中的各种效应理论都在不断发展,引人注目。本文针对周内效应做了相关研究。结合实际,以往周内效应论文模型存在收益序列的自相关性,本文对EGARCH模型进行修正,消除了其自相关性,并利用修正的AR-EGARCH模型对上证综指1997-2010年数据进行实证检验。研究发现上海股市存在收益与波动的周内效应:收益存在负的周四效应,波动存在正的周一效应和负的周二效应,另外发现上海股市存在杠杆效应。     

公司盈利不稳定性对中国股市动量策略的影响研究

通过分析市场盈利不稳定性对中国股市动量策略收益的影响,构建了包含动态权重的动态动量策略。研究发现,市场盈利不稳定性对中国股市的动量效应具有显著为负的影响,并且该影响在不同的市场涨跌状态下表现出非对称性。具体而言,当盈利不稳定性升高时,动量效应减弱,并且当市场处于上涨状态时,上述关系更为显著。相对于传统的静态动量策略,基于市场盈利不稳定性所构建的动态动量策略表现出更强的择时能力,具备更为优异的市场表现,最高可获得13.62%的年化平均收益率,与之相比,传统静态动量策略的最高年化收益率仅为5.16%。     

基于残差收益的动量或反转效应:来自中国A股市场的经验证据

因不能有效反映股票盈利的相对强弱,基于总收益排序的动量或反转组合,通常包含大量高Be-ta值和小市值股票,承担着较大风险。为此,本文采用风险调整后的收益评价,即基于残差收益排序,考察中国A股市场月度数据的动量或反转效应,结果发现:在全样本阶段存在显著的残差反转效应,不存在残差动量效应,这在股权分置改革之后更明显;相对于总收益反转组合,残差反转组合不仅具有更高的显著收益和Sharpe比率,还具有较小的系统风险,并受公司规模因素影响较小。     

金融市场MAX效应的影响因素研究 ——基于价格视角

金融市场的变量虽然纷繁复杂,但价格因其直观性和重要性,成为金融市场参与者最易观察且难以忽略的变量,正因如此,价格对市场参与者的心理和行为产生了深刻影响.以中国股市2004年1月至2020年6月的数据为样本,探究价格因素会如何影响由追涨行为所导致的M AX效应.实证结果发现:投资者的追涨勇气和热情明显会受到价格影响,即当反应市场整体价格水平的股指指数近期上涨或波动率越小时,亦或当个股价格越低于其前期最高价、越低于投资者购买价时,投资者越乐于追涨具有"高极端收益"的个股,M AX效应也随之会更显著.     

股市资金面和持股结构对股票流动性的影响 ——基于深市订单深度和买卖价差的实证检验

股市资金面和持股结构能否对个股流动性产生影响?本文基于2015年股市异常波动期间深市上市公司样本,构建固定效应面板模型,实证检验了股市资金面水平和持股结构对个股订单深度和买卖价差的影响,旨在进一步揭示股票市场整体流动性与微观个股流动性间的关系,为监管部门提供政策依据.分析结果表明:第一,股市资金面充裕水平对个股流动性有全局性正向影响,股票市场整体的流动性越高,越有助于提升个股的流动性;第二,持股结构这一异质性因素对个股流动性有负向影响,持股集中度越高、股东数越少,个股的流动性则相对越差,也意味着股价信息含量可能更低.这为管理层掩饰坏消息从而加大股价崩盘风险提供了新的补充解释.本文研究结论有助于理解股票流动性变化的原因,丰富了相关领域研究,并为监管部门制定相关政策、维护市场稳定运行提供了新视角.     

对小公司效应、价值股效应、动量效应以及反转效应的实证研究——基于三因子模型

本文分析了行为金融学中小公司效应、价值股效应、动量效应以及反转效应对于中国股票市场的影响,以A股市场2000-2018年数据为研究样本,基于Fama-French三因子模型,探究结合行为金融因素的多因子模型能否较好地拟合股市。研究发现,A股市场不同板块对于各个因子的偏好与权重不同,而单一股票也很难通过多因子去很好地解释超额收益,而本文希望通过实证分析来展示非理性因素对于金融市场的影响。     

中国股票市场流动性溢价实证研究——基于1988至2011年个股面板数据的分析

本文以个股为切入点,将换手率和Amihud流动性比率作为流动性因子代表指标,建立基于面板数据的个体固定效应变截距回归模型,对我国A股股票市场流动性溢价存在性进行理论剖析和实证检验.实证结果表明,股票预期收益与个股换手率呈反向相关关系,与个股Amihud流动性比率呈正向相关关系.同时,分别从我国股市这两种流动性指标出发得出完全一致的结论,即我国股市存在显著的流动性溢价,流动性证实是股票预期收益的关键影响因素之一     

中国A股市场动量效应与“动量崩盘”现象研究

动量效应作为一种金融异象,广泛存在于各个市场。然而在丰厚收益的背后却存在着巨大的风险,学术界称之为"动量崩盘"。本文在确定中国A股证券市场动量效应的基础上,进一步研究了动量组合的风险性质。结果表明:A股市场存在周度的动量效应;且该周度效应无法被CAPM和Fama-French三因子模型所解释;A股的周度动量效应没有出现普遍存在于其他动量市场的"动量崩盘"现象,表明在A股市场实施动量策略,不仅收益比美国市场更丰厚,而且风险更小;而动量组合在牛熊市中不对称的收益表现,使得动量收益可以和股票期权一样被市场预计波动率所解释。     

证券市场非完全知情交易者是风险助推者吗?——基于Kyle模型的分析

跟庄散户等非完全知情交易者的交易行为会影响证券市场上的其他参与者。本文基于Kyle模型的拓展研究表明:当市场流动性下降时,知情交易者会减少交易;部分知情的噪声交易加入后会使得知情交易者的预期收益下降;当非完全知情交易者的委托单流恰好完全跟踪股票价值时,内幕信息持有者的信息将不能操纵股价波动。从抑制知情交易者的内幕交易行为的角度讲,非完全知情交易者有助于推动证券市场交易的透明化、公正化,进而减少整个市场潜在的金融风险。     

Asset pricing in China's domestic stock markets: Is there a logic?

China's stock markets have grown rapidly since their inception and have become an increasingly important emerging market for international investors. However, there are few systematic studies on how asset prices are formed in Chinese domestic equity markets; popular financial media even depict the market as irrational. In this paper, we study the asset pricing mechanism in the nascent Chinese stock markets, with the objective of identifying variables that capture the cross-sectional variation in average stock returns. We focus on the effects of various market imperfections in China. We find that while the market risk (beta) is not priced, there is a significantly negative relationship between firm-specific risk and expected returns. Chinese investors are willing to pay a significant premium for more liquid stocks or for dividend-paying stocks. Furthermore, investors value local A-shares more if there are offshore counterparts (e.g., B- and H-shares) for foreigners, implying that a Chinese firm with a foreign shareholder base has a lower cost of capital, ceteris paribus. Lastly, as with U.S. and other mature markets, firm size and the book-to-market ratio are systematically related to stock returns. Given market imperfections, stocks are priced rather rationally in China, despite the widespread perception to the contrary.     

南橘北枳:A股市场的经济关联与股票回报

本文系统检验并比较了中国A股市场中行业动量、区域动量、供应链动量以及科技关联动量等经济关联动量的显著性及预测周期。本文发现,中国股票市场中经济关联因子呈现出与美国股票市场不同的规律,在月度层面行业动量显著,而科技关联因子只在周度上具有显著的预测能力。进一步分析科技关联动量发现,中国股票市场中科技关联因子能预测目标公司未来1-3周的股票收益和未来基本面的变化,据此构建的多空策略能够产生周度0.16%的超额收益(年化8.67%);机制检验发现,科技关联因子预测期短的原因是由于中国股票市场中存在较多具有博彩倾向的散户投资者;有限注意和市场摩擦两个机制检验证明科技关联动量源自错误定价。进一步检验发现,科技关联动量在国有企业和创新政策颁布后更加显著。本文补充了现有A股市场的动量研究,有助于理解中国股票市场规律、提升资本市场有效性。     

我国上市公司高送转公告效应的实证研究

为检验上市公司定高送转预案公告发布对其股票价格的影响,本文以2009年至2010年沪深两市推出高送转预案的285家上市公司为样本,选取公告日前10日至公告日后20日为事件窗口,运用事件研究法对高送转公告效应进行实证研究。结果表明：中国股市具有明显的高送转公告效应,上市公司高送转预案公告发布前后股票具有显著的正价格效应,会产生持续的累计异常正收益;然而,由于信息不对称,部分投资者通常会提前获得有关高送转的内幕信息并提前买入,并以此获得可观的超额收益,而普通投资在公告发布后买入只能获得小部分的超额收益并且需要承担更大的风险。     

The price impact of foreign institutional herding on large-size stocks in the Taiwan stock market

This study constructs a panel threshold regression model to explore the price impact of foreign institutional herding of firms listed in the Taiwan Stock Exchange during January 2000 to June 2008. Our panel threshold model is constructed to explore the price impact of foreign institutional investors?? herding in the Taiwan stock market after controlling the firm size. By examining the presence of threshold effect, this study analyzes whether firm size would obviously and asymmetrically affect the explanation for the effect of changes in foreign investors?? share ownership on abnormal returns. The empirical results of this study find the significant evidence of threshold effect which divides the stocks into large-size and small-size firms. It is found that foreign institutional investors in the Taiwan stock market tend to hold large-size stocks listed in the Taiwan Stock Exchange. There is an apparent increase in the subsequent abnormal returns on large-size stocks bought in bulk by foreign investors. The signals of changes in share ownership initiated by foreign institutional investors would reveal further information for improving the performance of asset reallocation decisions in Taiwan. The panel threshold model constructed in this paper well describes the price impact of institutional herding yet eschews the possibly subjective data snooping issue resulting from the two-pass sorting method as proposed by previous related researches.     

投资者情绪是导致我国投资者对市场信息出现反应偏差的原因吗：基于贝叶斯分位数回归模型的研究

本文使用贝叶斯分位数回归模型实证分析包含投资者情绪的投资者最优选择模型,结果表明：投资者情绪对于股票收益率存在非线性的正向影响,这是造成投资者对于市场信息出现反应偏差的一个重要原因.同时,市场信息和投资者情绪指标对于我国股票收益率都有着较大的影响作用;当股票出现不同涨跌幅时,市场信息对于股票收益率的影响有着较大的差异性.而考虑了投资者情绪指标之后,投资者对于市场信息的反应偏差明显减小,说明投资者情绪是造成我国投资者对于市场信息出现过度反应和反应不足的重要原因.我国投资者应该树立起良好的投资意识和心态,避免潜在的投资损失.     

Momentum and Foreign Investors: Evidence from the Korean Stock Market

Abstract:

We examine whether the price impact of foreign investors on the Korean stock market from December 2000 to February 2007 generated a momentum phenomenon. In our empirical results, foreigners seem to have exerted a significantly positive impact on prices in “up” markets (periods of positive stock returns), but have had little impact on prices in “down” markets (periods of negative returns). We document that the impact of foreigners’ trades is concentrated in large companies. Most importantly, when the market is in the up state, the returns of stocks of large companies that were positively affected by foreign investors in the previous six-month period continue to increase in the subsequent six-month period. As a result, the subsequent six-month return on a past “winner” stock portfolio is significantly higher than that on a past “loser” stock portfolio. This brings to mind a momentum phenomenon that has been reported not to exist in the Korean stock market.     

Online Search Frequency,Retail Investor Overreaction,and the Cross-Section of Stock Returns: Evidence from the Chinese Stock Market

I find a strong negative relation between online search frequency and future returns on the Chinese stock market. I suggest that this effect captures retail investor overreaction to unexpected signals, because online search frequency reflects the efforts made by investors to obtain firm-specific knowledge. The effect is particularly strong in stocks with high information uncertainty (high analyst dispersion, big past earnings surprises, low analyst coverage, and large trading volume), whose intrinsic values are difficult or costly for investors to estimate. Online search frequency as a direct indicator of retail investors’ reaction to signals also sheds light on the idiosyncratic volatility (IVOL) puzzle. I find that this puzzle is more pronounced in high-search-frequency subsamples and disappears in low-search-frequency subsamples. Further evidence shows that high search frequency strengthens the negative IVOL effect in stocks with positive signals but weakens this effect in stocks with negative signals. I suggest that the IVOL puzzle in the Chinese market can be partially explained as a reversal following overreaction to positive signals by retail investors.     

动量交易策略及我国股票市场实证分析

动量交易策略指的是事先针对股票收益及交易量设定过滤规则,一旦股票收益或者股票收益和交易量同时满足过滤规则就买入或卖出股票的交易策略。动量交易策略的理论基础是行为金融学。国外投资者已经成功地在实践中应用了该策略。我国股票市场是否存在动量效应,还未形成统一的结论。在总结国内外学者研究方法的基础上,利用目前可用的数据,对我国股票市场在中期条件下动量交易策略的适用性进行了实证研究。但得出的结论并不支持存在动量效应。     

Futures Market Sentiment and Institutional Investor Behavior in the Spot Market: The Emerging Market in Taiwan

This paper investigates whether and how futures market sentiment and stock market returns heterogeneously affect the trading activities of institutional investors in the spot market in Taiwan. Our empirical results suggest that foreign investors are net sellers whenever futures market sentiment is bullish and net buyers when investor sentiment is bearish. The two types of domestic institutional investors have poor sentiment timing abilities and the price-pressure effect may account for the behavioral differences among institutional investors. In addition, all three institutional investors are momentum traders. Nevertheless, the momentum trading of foreigners is consistent with an information-based model and that of two local institutional investors, as behavior-based models suggest. This indicates that the same trading momentum strategy can lead to different outcomes for different investors, and both information- and behavior-based momentum trading can exist contemporaneously in the Taiwanese stock market.     

Microstructure and reverse stock splits

In this paper we show that, similar to NYSE/AMEX stocks, NASDAQ stocks exhibit significant ex date returns for reverse stock splits. Although the 10-day cumulative return after the ex date is close to –10%, this does not violate market efficiency, because the average bid-ask spread for the reverse split stock is at least double this return. We also document that these large negative returns are mostly due to a drop in the ask price while bid prices barely change at all. Furthermore, the ex date returns are negatively related to trading volume.These results suggest that there is abnormal selling and a significant buildup of market makers' inventories near the ex date. To reduce the inventory buildup, market makers lower ask prices to induce buying by investors, resulting in the observed negative returns. Lowering bid prices, an alternative strategy for reducing inventories, is not attractive to market makers due to competitive factors and the reduction of commissions associated with a smaller number of transactions. Notably, selling investors have no incentives to sell their stocks early to avoid the observed negative ex date return, since this return is largely an ask price phenomenon and does not represent realized returns to sellers.