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。     

投资者结构是中国股票市场定价因子吗？

机构投资者持股比例可能会影响股票的预期收益，本文尝试探究投资者结构是否是中国股票市场定价因子。本文利用A股数据构建投资者结构因子，并将该因子加入Carhart四因子模型中进行实证回归。研究发现：(1)投资者结构是沪深股票市场定价因子，该结论通过了稳健性检验；(2)相对于沪深主板市场，创业板与科创板市场的投资者结构因子溢价更高；(3)新冠疫情提高了沪深股票市场的投资者结构因子溢价。本文补充了A股市场在资产定价方面的研究，为A股市场投资端改革提供了经验证据。     

基于中国股市的动量策略和反转策略盈利性研究

本文测试了中国股票市场中A股的反转策略和动量策略的盈利性,实证结果证明了短期内的动量收益,而反转收益存在于中长期和长期。在对两类收益的原因探析中,本文证明反转收益部分归因于规模效应。Beta因素对两类收益都没有解释力。本文同时还测试了Fama-French三因素模型,发现包含市场风险、规模差异和账面市场价值比在内的三类公共因素均不能有效解释反转收益和动量收益。     

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。     

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。     

市场流动性风险能解释价值溢价吗?

文章以1997年1月～2017年12月的沪深A股为研究对象,从流动性风险角度检验价值溢价的风险来源,对价值股和成长股的流动性风险与收益进行对比研究,分析中国股票市场中流动性因子对价值因子的解释能力。研究发现:价值股的市场流动性风险大于成长股,价值溢价的成因是价值股承担了更高的市场流动性风险,从风险补偿角度解释了价值溢价;同时发现在中国股票市场中投资因子与盈利因子并不能解释价值因子,而流动性因子可以解释。     

分析师修正信息、基本面分析与未来股票收益北大核心CSSCISSCI

本文基于日历时间组合方法检验中国A股市场分析师修正信息的投资价值。研究发现,分析师发布的盈余预测修正和投资评级修正最具信息含量,投资者既未充分意识到两类修正的信息含量,也未充分意识到明星分析师和普通分析师能力的差别。根据分析师盈余预测修正和投资评级修正构建套利组合,能分别获得月均1.34%和0.92%的经三因子模型调整的超额收益。本文进一步指出,分析师修正信息的投资价值来源于其基本面分析的能力。分析师盈余预测修正和投资评级修正能够显著预测公司未来的盈利能力、标准化未预期盈余和盈余公告窗口期超额收益,并且套利组合的超额收益集中在盈余公告窗口期。本文的结论对于理解分析师在资本市场中发挥的作用、提高市场有效性具有重要意义。     

大宗交易对股价波动的羊群效应研究

以2018-2020年沪深A股发生大宗交易的上市公司为样本,实证检验了上市公司大宗交易定价对其二级市场股票价格波动的影响机理。结果表明：投资者羊群效应与股票超额收益显著正相关;大宗交易折溢价率与股票短期超额收益显著正相关;股票市场的伪羊群效应会减弱大宗交易对股票价格的短期影响。获取大宗交易定价信息的投资者理性与否决定了大宗交易定价对二级市场股票价格作用的强弱。进一步研究发现：沪深A股市场短期内伪羊群效应显著,长期内真羊群效应显著;这充分表明中国股票市场的资产定价相对合理,投资者处于有限理性状态。     

基于货币供应周期的股市周期拐点判别与资产配置研究

本文拟以中国A股市场为研究对象,尝试找出中国货币周期转换与股市周期之间的关联,考察货币周期不同阶段中股票市场的表现与行业轮动规律,并在此基础上给出适宜的资产配置策略。     

价值性投资还是博彩性投机？——中国A股市场的MAX异象研究

本文利用1995—2017年中国A股上市公司公开数据实证检验了A股市场中的MAX异象,并从博彩性投机和有限套利视角深入探讨了异象的形成持续机制。结果显示:中国A股市场存在显著的MAX异象,个股当月MAX越小下月收益率就越高,构造多空组合可实现年化15.72%的收益。在投资者博彩性投机心理作用下,短期内MAX有惯性传递特征,投机性特征越强、内在价值越低的股票异象越显著。进一步实证分析发现:套利限制对MAX异象具有正向强化作用,套利限制越强异象越显著,多空策略组合获得的收益越高。本文的研究不仅有助于更好地理解中国股市中MAX异象,也对提升市场有效性、减小异象的影响有实践意义。     

Investor Attention and Stock Returns: International Evidence

This article examines the asymmetric/discriminative effects of investor attention on expected stock returns among 15 markets through economic expansions and recessions. The predictive power of attention tends to be short-lived and weakens the autocorrelation within returns. Accounting for business cycles not only confirms that the predictability of attention endures with volatility but also explicates the asymmetric effects that underlying pessimism functions better. International evidence contributes to the literature on investor attention and reveals the discrepant effects of attention with three levels of market efficiency: semi-strong, stronger than semi-strong, and weak.     

Are good-news firms riskier than bad-news firms?

This paper examines the relative risk of good-news firms, i.e., those with high standardized unexpected earnings (SUE), and bad-news (low SUE) firms using a stochastic discount factor approach. We find that a stochastic discount factor constructed from a set of basis assets helps explain post-earnings-announcement drift (PEAD). The risk exposures on the pricing kernel increase monotonically from the lowest to highest SUE sorted portfolios. Specifically, good-news firms always have higher risk exposures than bad-news firms in both 10 SUE sorted portfolios and 25 size and SUE sorted portfolios. However, the estimated expected risk premium is too small to explain the observed magnitude of returns on the PEAD strategy. Our risk adjustment can explain only about one-fourth of the total magnitude of the average realized return to the PEAD strategy. As a result, the average risk-adjusted returns of earnings momentum strategies are mostly positive and significant. Overall, our results support the view that at least some portion of the returns to the earnings momentum strategies examined represent compensation for bearing increased risk.     

In name only: Information spillovers among Chinese firms with similar stock names during earnings announcements

We examine whether investors' attention on salient firm characteristics affects information spillovers during corporate earnings announcements. For market participants in China, the stock name is a salient feature of listed companies. We find that the market reaction of non-announcing firms to earnings reports of announcing firms is greater across firms with similar stock names. The incremental information spillovers among similarly named stocks are stronger for larger announcing firms and on days with fewer earnings announcements. The incremental information spillovers between similarly named stocks do not fully reverse in the post-announcement period, consistent with persistent investor behavior predicted by the salience theory. There are also significant return comovements among similarly named stocks. Our findings suggest that investors with limited attention are likely to focus on salient stock names and overestimate the economic connections between similarly name stocks. Our study extends the behavioral finance literature by showing how investors' attention on salient firm features can bias their reaction to unrelated peer disclosures.     

预防性监管与公司产能过剩--基于年报问询函的研究证据北大核心

本文研究年报问询函这一预防性监管制度能否推动公司去产能,并探究其作用机制和经济后果。研究发现,相比未被问询的公司,被问询的公司收函后产能过剩水平显著下降;该结果在媒体负面报道较多的公司、地方政府治理水平较高的地区中更为明显,表明年报问询函通过降低市场、政府与公司间的信息不对称,强化市场和政府的治理效应,进而有效促使公司去产能。影响机制检验表明,年报问询函主要通过优化资源配置、减少代理问题作用于去产能。经济后果方面,年报问询函会提升被问询公司的生产效率和经营业绩。     

The Equity Share in New Issues and Aggregate Stock Returns

The share of equity issues in total new equity and debt issues is a strong predictor of U.S. stock market returns between 1928 and 1997. In particular, firms issue relatively more equity than debt just before periods of low market returns. The equity share in new issues has stable predictive power in both halves of the sample period and after controlling for other known predictors. We do not find support for efficient market explanations of the results. Instead, the fact that the equity share sometimes predicts significantly negative market returns suggests inefficiency and that firms time the market component of their returns when issuing securities.     

Economic policy uncertainty and momentum

We show that a news‐based measure of economic policy uncertainty (EPU) negatively forecasts momentum. A 1‐standard‐deviation increase in EPU is associated with a 1.11% decrease in risk‐adjusted momentum returns. The predictive power of EPU is robust after controlling for previously documented economic state variables and macroeconomic uncertainty. We provide an explanation for these results from the perspective of a fund flow‐induced trading mechanism and offer direct empirical support. The literature documents that momentum can be partially attributed to performance‐chasing mutual fund flows. We find that this flow‐induced mechanism functions more effectively in low EPU states, thereby generating stronger stock momentum.     

Economic policy uncertainty,investor attention and post-earnings announcement drift

How the market incorporates information into stock price is a core issue in finance. This study focuses on the impact of economic policy uncertainty (EPU) on the stock prices information efficiency of China's A-share market and underlying role of investors' attention allocation mechanism. This study analyzes the information efficiency of stock prices using the sensitivity of stock cumulative abnormal return to earnings information across different windows following earnings announcement. Based on the earnings announcement events of listed companies in China's A-share market, this study presents an empirical study of the aforementioned issues using event study and regression analysis methods. The following results are seen: (1) EPU aggravates the underreaction of stock price earnings information and the post-earnings announcement drift in the A-share market. (2) Under highly uncertain economic policies, investors show a limited attention allocation pattern of devoting increasing attention to macroeconomic policies and decreasing attention to earnings information, which leads to a decrease in the information efficiency of stock price. This study also analyzes the heterogeneity of the influence of EPU on stock price information efficiency using the institutional shareholding ratio. The results show that increasing institutional shareholding does not reduce the adverse effects of EPU on the information efficiency of stock prices. This study not only provides empirical evidence for Brunnermeier, Sockin, and Xiong (2022) and rational inattention theory, but also reveals that institutional investors show similar behavioral characteristics to retail investors in China's stock market. The results of this study have policy significance for improving the information efficiency of stock market.     

Uncertainty triggers overreaction: evidence from corporate takeovers

Behavioural finance models suggest that under uncertainty, investors overweight their private information and overreact to it. We test this theoretical prediction in an M&A framework. We find that under high information uncertainty, when investors are more likely to possess firm-specific information, acquiring firms generate highly positive and significant gains following the announcement of private stock and private cash acquisitions (positive news) while the market heavily punishes public stock (negative news) deals. On the other hand, under conditions of low information uncertainty, when investors do not possess private information, the market reaction is complete (i.e. zero abnormal returns) irrespective of the type of acquisition. Overall, we provide empirical evidence that shows that information uncertainty plays a significant role in explaining short-run acquirer abnormal returns.     

中国A股市场存在品质溢价吗?

本文从价值投资的核心理念出发,基于盈利性、成长性、安全性、分红能力四个维度构建复合品质指标,并通过分析品质溢价在中国A股市场中的存在性来探讨价值投资的可行性和有效性。实证结果表明:(1)中国A股市场上存在显著为正的品质溢价,且品质溢价在控制其他相关变量后依然稳健存在;(2)高品质股票具有大市值、高成长特征,且品质溢价在大市值、高盈利的分组中更加显著;(3)品质溢价在不同时期下均能稳定存在;(4)中国A股市场上的品质溢价并非源于高风险承担,相反,由正向反馈偏好、博彩偏好、套利限制引起的错误定价有助于解释品质溢价。本文结论佐证了价值投资策略在中国A股市场的可行性和有效性,为培育良好投资理念、抑制过度投机、促进中国股市合理健康发展等提供了经验证据。     

Firm characteristics and long-run stock returns after corporate events

The well-documented abnormal long-run buy-and-hold returns to firms issuing equity in initial public offerings and seasoned equity offerings, firms bidding in mergers, and firms initiating dividends can be attributed to imperfect control-firm matching. In addition to firm size and market-to-book ratio, event firms on average differ from control firms in terms of idiosyncratic volatility, liquidity, return momentum, and capital investment, each of which also explains returns. We propose a simple regression-based approach to control for differences in firm characteristics across event and control firms, and we show that long-run abnormal returns do not differ significantly from zero for event firms in the 1980 to 2005 period. The returns to event firms are, therefore, consistent with patterns known to exist for the broad stock market and do not require event-specific explanations.