A股市场上的“中石油魔咒”现象及其解释

文章针对A股市场上流传甚广的"中石油魔咒"现象,首次从基本面角度进行了解释,认为造成这一现象的根本原因是国际原油价格对我国股票市场存在显著的负向溢出效应,即当国际原油价格上涨时,对中石油个股产生利好,但对整体宏观经济却构成利空,因而中石油股票价格上涨,整个股票市场却会下跌。进一步研究还发现,这种负向溢出效应具有非线性特征,表现为国际原油价格上涨对股票市场的打压力度要大于其下跌对股票市场的提升力度。这提醒A股投资者相对于国际原油价格下跌,要更加关注国际原油价格上涨带来的投资风险。     

Do net positions in the futures market cause spot prices of crude oil?

The last decade has witnessed sharp increases in the price of crude oil. There are two possible explanations for these increases: dramatic increases in financial firms' position in the oil futures market and recent increases in oil prices from changes in economic fundamentals. This paper examines the causal relationship between the net financial position and the crude oil price by using three types of Granger non-causality tests: the classical Granger non-causality test, a robust Granger non-causality test and a Granger non-causality test in quantiles. The empirical results provide some evidence of causality from the net financial position to the spot price of crude oil. In addition, futures prices serve as a transmission mechanism underlying the causal relationship between the net financial position and the crude oil price.     

The effect of oil prices on stock prices: fresh evidence from asymmetric causality tests

This article investigates the causal impact of oil prices on stock prices in each G7 market as well as in the world market. An asymmetric causality test developed by Hatemi-J is used for this purpose. Since the underlying data appears to be non-normal with time-varying volatility, we use bootstrap simulations with leverage adjustments in order to produce more reliable critical values than the asymptotic ones. Based on symmetric causality tests, we find no causal effect of oil prices on the stock prices of the world market or any of the G7 countries. However, when we apply an asymmetric causality test, we find that increasing oil prices cause stock prices to rise in the world, the U.S. and Japan while decreasing oil prices cause stock prices to fall in Germany. This may imply that the world, the U.S. and Japanese stock markets consider increases in oil prices as an indicator of good news as this may mean that there is an increase in oil demand due to an expected growth in the economy while the German stock market treats decreasing oil prices as a signal of an expected contraction in the economy.     

Diversification and optimal hedges for socially responsible investment in Brazil

This study contributes to the literature on socially responsible investing by examining the diversification potential of commodities, specifically oil, gold and clean energy together with the Brazilian Corporate Sustainability Index (ISE). Multivariate GARCH models are used to model volatility spillovers and conditional correlation in pairs of stocks containing ISE. Specifically, A-BEKK and A-DCC models with spillovers are estimated. The models’ results are used to compute and analyze the optimal weights and hedge ratios for stock portfolio holdings. The greatest benefit from diversification is obtained through the acquisition of gold and then OVX.     

Optimization agricultural production under financial risk of water constraint in the Jordan Valley

Using high-frequency data the co-movements among crude oil prices are analysed in order to address the question of regionalization of the world crude oil market. Time-series econometrics in the form of error-correction modelling is applied for daily crude oil price data covering the time period 1988 to 2004 and in this framework topics like weak and strong exogeneity among three major oil prices – represented by Brent, OPEC and Texas (WTI) – are addressed. The empirical results are that causality is most likely bi-directional among these crude oil prices – and hence rejecting a regionalization hypothesis of the global oil market – and also an influence from the OPEC oil price towards Bent and WTI, which are usually claimed to have a benchmark role.     

股票价格、实体经济与货币政策研究——基于我国1997-2011年的经验证据

本文运用格兰杰因果关系检验和向量自回归方法分析了1997年1月至2011年6月我国股票价格、GDP、通货膨胀率和货币政策的关系,实证结果表明,在中国,股票价格对通货膨胀的效应为正向,即股市上涨能带动通货膨胀水平的上涨。股票市场对GDP的影响短期内主要表现为替代效应,长期来看,则是财富效应和投资效应占主导;同时,货币供应量和利率对股票价格均有影响,但影响均不显著。通过格兰杰因果关系检验发现,利率变动导致货币供应量和股票价格发生变化。而货币供应量的变化影响着通货膨胀,也一定程度影响利率和股票价格。通过广义脉冲响应发现,中国人民银行紧缩性的利率政策并不能抑制股票价格上涨。增加货币供给短期内能够推动股市上涨,但长期对股市仍没有效果。     

Crude oil and BRICS stock markets under extreme shocks: New evidence

In this paper, we propose an extreme Granger causality analysis model to uncover the causal links between crude oil and BRICS stock markets. Instead of analyzing the average causal relationship, as is usually done, we first decompose the data into three cumulative components and investigate the causality between different combinations of extreme positive, extreme negative and normal shocks. These types of combinations can describe all facets of the interactions between crude oil and BRICS stock markets, especially under extreme shocks. In contrast to the results obtained by the traditional Granger causality test, our empirical findings demonstrate that the effect of oil price changes on the stock markets is stronger under extreme circumstances than under normal circumstances. Furthermore, large upward or downward oil price changes have an asymmetric impact on extreme upward or downward stock price changes. Finally, robustness checks verify the rationality and validity of the extreme Granger causality analysis.     

Oil price risk in the Spanish stock market: An industry perspective

This study examines the sensitivity of the Spanish stock market at the industry level to movements in oil prices over the period 1993–2010, paying special attention to the presence of endogenously determined structural changes in the relationship between oil price changes and industry equity returns. The empirical results show that the degree of oil price exposure of Spanish industries is rather limited, although significant differences are found across industries. The oil price sensitivity is very weak in the 1990s, a period of fairly stable and low oil prices. Instead, the link between crude oil and stock prices seems to have increased during the 2000s, becoming primarily positive. This evidence highlights the key role played by aggregate demand-side oil price shocks associated with the global real economic activity in the link between oil price fluctuations and the Spanish stock market.     

Long-run waves or short-run fluctuations – what establishes the correlation between oil and food prices?

The strong correlation between food prices and energy prices has gained much attention in the public debate. In this article, we focus on the so-called excess co-movement, which is the correlation between crude oil price and the prices of food commodities after controlling for economic activity. We use a frequency domain Granger causality test to analyse short-run and long-run relationships between crude oil prices and prices of food commodities. For important biofuel inputs like maize, soybeans, rapeseed and EU sugar, we find evidence for long-run Granger causality in particular for the period after 2007. This supports the hypothesis that the increasing biofuel production creates the link between the prices of crude oil and food commodities. However, we also find short-run Granger causality for various food commodities. This result is more in line with herd behaviour or speculation in commodity markets.     

Impact of oil prices on firm stock return: industry-wise analysis

The study investigates the impact of oil prices on firm-level stock returns in case of Pakistan over the period 1998–2014, as this relationship is neglected by the previous literature. By using the panel data estimation, the results of full sample indicate significant positive effect of oil price changes on firm stock returns in the same period, whereas the lagged oil price changes have significant negative effect on firms’ stock return. Moreover, the industry-level analysis also confirms the similar findings; results indicate significant positive impact of oil price on firms’ stock return in full sample, textile, chemical and miscellaneous industry, while the lagged oil price changes negatively affect the stock returns of full sample and all the industries except tobacco, jute and vanaspati industries. The study confirms that rise in oil price transfers a positive signal in the stock market that boosts the firm-level stock returns in Pakistan. In contrast to the negative shocks, the stock returns are significantly affected by the positive oil price shocks.     

卖空机制、股价信息含量与暴跌风险--基于融资融券交易的经验证据

文章利用我国逐步推出融资融券交易的自然实验机会,运用双重差分的研究设计,考察了卖空机制对股价反映负面消息效率的影响。文章以2007-2012年的数据为样本研究发现：相对于非标的股票,融资融券标的股票在成为标的之后,其股价对市场的向下波动及时做出了调整,使得股价对市场正负向波动反应之间的不对称性显著降低,表明标的股票更加及时和充分地吸收了有关公司价值的负面信息;同时,相对于非标的股票,融资融券标的标的股票在成为标的之后,其股价暴跌风险显著降低。文章结果表明,我国股市推出融资融券交易后,卖空机制提高了市场对标的股票负面消息的定价效率。     

保险资金持股与股价崩盘风险——市场“稳定器”还是崩盘“加速器”?

现阶段,有关保险资金持股与资本市场稳定相互关系的讨论多止于推测,少有学者以大样本数据进行实证考察。在理论上,保险资金持股上市公司,一方面可以抑制经理人负面信息隐藏,作为市场“稳定器”降低股价暴跌风险;另一方面,也能引发投资者跟风炒作,导致市场情绪高涨和股价高估,成为股价崩盘风险的“加速器”。本文基于2007—2016年中国沪深两市A股上市公司的数据,实证分析保险资金持股上市公司是否加剧市场暴跌及其作用机制。结果显示:保险资金持股加剧了股价崩盘风险,是公司股价崩盘的“加速器”。这一结论在经过DID模型、工具变量回归、PSM+OLS等内生性分析,以及稳健性检验之后依然成立。进一步研究表明,相比于民营、小型和财产保险公司,在股市投资规模更大的国有、大型和人寿保险公司更能引发市场跟风炒作,加剧股价崩盘风险;不过,当保险资金作为前十大股东参与公司治理时则能够降低股价崩盘风险。本文不仅为保险资金持股与资本市场稳定相互关系的讨论提供了经验证据,也为规范保险资金股权投资,维护资本市场稳定提供有益借鉴。     

Market Underreaction and Overreaction of Technology Stocks

Several studies have assessed stock market under- or overreaction of stocks and there is some agreement among them. However, there is much disagreement about what constitutes market underreaction or overreaction, and the conditions that cause it. The substantial variation in results among studies may be partially attributed to the types of firms that are contained in any sample. We investigate this premise by focusing on a sample of technology stocks that experienced an extreme change in stock price, along with a corresponding control sample of non-technology stocks that experienced a similar extreme change in stock price on the same day.

Based on the subsequent stock price behavior of each sample, we find a greater degree of overreaction within extreme positive changes in technology stock prices (winners) than in non-technology stock prices. In addition, we find a greater degree of underreaction within extreme negative changes in technology stock prices (losers) than in non-technology stock prices. When considering winners and losers collectively for technology and non-technology firms, it appears the market is overoptimistic when it initially revalues technology stock prices relative to non-technology stock prices.

The degree of under- or overreaction of technology stocks varies within the sample of technology stocks, and is conditioned on firm-specific characteristics. Overall, our results suggest that technology stocks exhibit unique stock price behavior subsequent to an extreme change in price, and that this unique behavior can even vary among technology firms according to firm-specific characteristics.     

国有机构投资者持股能提升企业投资效率吗?

具有国资背景的机构投资者,对于资本市场平稳发展具有重要意义。本文基于我国2015—2019年A股上市公司样本,考察持股对企业投资效率的影响。研究发现,持股显著提升了企业投资效率,并且该影响在代理冲突更严重和所处信息环境更不透明的公司中更加显著。机制检验表明,降低企业内外部信息不对称和代理成本是持股提升企业投资效率的重要渠道。进一步研究发现,国有机构投资者持股时间越长,对企业非效率投资的治理效果越好;细分国有机构投资者类型后发现,致力于长期维护资本市场稳定和上市公司长期健康发展的证金公司和汇金公司对企业投资效率的提升作用显著,但没有发现“救市”基金和外管局旗下的投资平台对企业投资效率有提升作用。研究结论从企业投资效率视角为国有机构投资者持股在微观企业日常经营中发挥的治理作用提供了新颖的经验证据,对进一步提高我国上市公司质量具有启示意义。     

An investigation into the dynamic relationship between international and China’s crude oil prices

This article studies the dynamic relationship between international (WTI, Brent and Dubai) and domestic (Da Qing) crude oil prices in China using threshold cointegration method. We find evidence of a long-run equilibrium relationship between each pair of international and Da Qing oil prices, favouring the market integration hypothesis. We also estimate asymmetric adjustments under the momentum threshold autoregressive (M-TAR) specification in a TVECM, and the results show that adjustments to eliminate disequilibrium happen faster when oil price spread increases than when it decreases. The long-run and short-run Granger causality tests support the notion that China has influence on the international oil markets. The results imply that China should open up its domestic and imported oil markets, and also establish a well-functioning crude oil futures market, as they are essential for arbitrage and hedging strategies.     

Oil prices and stock returns: nonlinear links across sectors

We present evidence of an asymmetric relationship between oil prices and stock returns. The two regime multivariate Markov switching vector autoregressive (MSVAR) model allow us to capture the state shifts in the relationship between regional stock markets and sectors. Results suggest that oil price risk is significantly priced in the sample used. The impact is asymmetric with respect to market phases, and regimes have been associated with world economic, social and political events. Our study also suggests asymmetric responses of sector stock returns to oil price changes and different transmission impacts depending on the sector analyzed. There is a high causality from oil to sectors like Industrials and Oil & Gas. Companies inside the Utilities sector were more able to hedge against oil price increases between 2007 and 2012. Historical crisis events between 1992–1998 and 2003–2007 do not seem to have affected the relationship between oil and sector stock returns, given the higher probability of remaining smoother. For all sectors there seems to be a turn back to stability from 2012 onwards. Finally, investors gain more through portfolio diversification benefits built across, rather than within sectors.     

Oil Price Shocks and Volatility in Australian Stock Returns

This paper examines the effect of oil shocks on return and volatility in the sectors of Australian stock market and finds significant effects for most sectors. For the overall market index, an increase in oil price return significantly reduces return, and an increase in oil price return volatility significantly reduces volatility. An advantage of looking at sector returns rather than a general index of stock returns is that sectors may well differ markedly in how they respond to oil price shocks. The energy and material sectors (as expected) and the financial sector (surprisingly) are out of step (in different ways) with results for the other sectors and for the overall index. A rise in oil price increases returns in the energy and material sectors and an increase in oil price return volatility increases stock return volatility in the financial sector. Explanation for the negative (positive) association between oil return (oil return volatility) and returns (volatility of returns) in the financial sector must be based on the association via lending to and/or holdings of corporate bonds issued by firms with significant exposure to oil price fluctuations and their speculative positions in oil‐related instruments.     

Corporate social irresponsibility,CEO overconfidence,and stock price crash risk

This study examines whether and how corporate social irresponsibility (CSI) influences stock price crash risk for firms with overconfident CEOs. We find that the positive association between CEO overconfidence and stock price crash risk as shown in prior studies is significantly weakened when firms have higher CSI concerns. As a result, our intriguing findings demonstrate that investors are less surprised at the negative news hoarded by overconfident CEOs of CSI firms, possibly because they are already aware of and have previously reacted to the socially irresponsible behavior in their daily operations.     

TERRORISM AND THE RETURNS TO OIL

The effect of terrorism on global oil prices has been largely explained through demand-side effects. We estimate an empirical model to re-examine the effect of terrorism on the price of global oil stocks across oil market regimes that reflect different supply constraints. We believe that terrorism will have larger impacts when global capacity is tight (i.e. when global demand is close to global supply). This means that any shock to capacity (say by conflict) should have the largest impact on profits before the first OPEC shock in the early 1970s. Since then, conflict shocks would not allow firms to exploit production in the same way, thus reducing the available profits that could be garnered by such production manipulation. If capacity constraints are binding when a conflict occurs, then we predict that a positive stock price reaction can be expected for oil firms from such a shock. We exploit a new panel dataset to investigate the relationship between oil profitability and conflict, using conflict data from the top 20 oil producing and exporting countries in the world. We show that in the later part of our sample, 1974–2005, as cartel behavior of OPEC member countries has diminished and as conflict has become more regular and thus the information surrounding it noisier, oil stock prices do not increase in response to conflict. However, in earlier capacity constrained eras, we find that oil stocks can in fact increase in response to conflict. In some cases, the impact of conflict may cause the return of oil stocks to increase by as much as 10 percentage points.     

资本市场开放与企业真实盈余管理——基于“陆港通”的经验证据

资本市场开放不仅是扩大国际融资、更好地利用国际金融市场的需要,而且对我国资本市场发育和上市公司行为具有多重外部治理效应。本文借助我国内地与香港资本市场互联互通机制这一准自然实验,研究资本市场开放对企业真实盈余管理的影响。研究发现:(1)总体上,“陆港通”机制的实施显著降低了标的公司真实盈余管理程度。(2)委托代理问题是企业进行盈余管理的重要原因,而“陆港通”机制开通后,能够缓解标的公司代理矛盾,进而约束管理层的真实盈余管理行为。(3)当资本市场信息环境改善、管理层面临较大股票抛售压力以及大股东监督力度较强时,“陆港通”抑制企业真实盈余管理行为的治理效果更强。本文结果表明,资本市场开放有助于提高我国上市公司财务信息披露质量及公司治理水平。