股票期权激励、高管解雇压力与公司风险承担

本文融合经典代理理论和行为代理理论两种理论观点,依据激励条件和行权有效期,将高管股票期权激励区分为严苛型和宽松型两类,分别研究其激励程度与公司风险承担水平之间的关系,并考察高管解雇压力对此二者关系的影响。研究结果表明：（1）严苛型高管股票期权激励程度与公司风险承担水平呈显著非线性关系,宽松型高管股票期权激励程度与公司风险承担水平呈显著线性负相关关系;（2）解雇压力滞后了严苛型高管股票期权激励程度与公司风险承担水平之间的非线性关系,并减弱了宽松型高管股票期激励程度与公司风险承担水平之间的负相关关系。     

公司投资冲击是否影响股票流动性——基于中国A股市场的经验证据

在宽松货币政策逐步退出、市值管理日益引起关注的背景下,股票流动性问题成为当前的研究热点。本文立足中国资本市场实际,实证研究了公司投资对股票流动性的影响及作用机理。研究发现:中国A股上市公司投资冲击显著降低公司股票的市场风险水平、增强股票流动性;在公司投资冲击增强股票流动性的作用过程中,公司市场风险具有部分中介作用。本研究在一定程度上厘清了微观公司投资影响股票流动性的作用机理,丰富了有关股票流动性微观前置影响因素研究。最后,就信贷资源配置结构、投资者教育及公司投资评价内容和公司市值管理等提出了政策建议。     

当前流行新名词（之三）

14．流动性 流动性是指资产能够以一个合理的价格顺利变现的能力，它是一种投资的时间尺度（卖出它所需时间）和价格尺度（与公平市场价格相比的折扣）之间的关系。流动性有三种用法或含义，一是指整个宏观经济的流动性，即在经济体系中货币投放量的多少，流动性过剩或紧缩最终会造成通货膨胀或者紧缩。二是在股票市场，是指参与交易资金相对于股票供给的多少，这里的资金包括场内资金和场外资金，如果股票供给不够或交易资金增长速度快于股票供给速度的话，即使公司盈利不变，也会导致股价上涨，反之亦然。三是对于股市中的个股，流动性指股票买卖活动的难易，流动性差的股票往往很难按理想价格卖出去，流动性好的股票往往换手率高。     

我国股票流通市场与经济增长关系的实证研究

本文通过研究股票流通市场规模,股票市场流动性和股票市场收益率等因素与经济增长之间的关系,发现股票流通市场的发展与经济增长之间基本成负相关的关系。     

探索"熨平"住房公积金资金流动性曲线波峰和波谷的有效途径

金融学上定义的流动性（Liquidity），是指资产能够以一个合理的价格顺利变现的能力，它是一种所投资的时间尺度（卖出它所需多长时间）和价格尺度（与公平市场价格相比的折扣）之间的关系。一般用流动性衡量资金集中使用的抵御能力，防范最终出现提兑风险。但同时，并不是流动性越大越好，因为在安全水平相同的情况下，流动性越强的资产往往收益率越低。     

股票回报与公司规模、市净率、市盈率之间的关系——基于中国A股市场的实证论证

本文运用经验研究方法,对中国A股市场上的股票回报与公司规模、市净率、市盈率之间的关系进行了检验。结果表明,规模、市净率及市盈率三个因素在不同的研究区间对股票回报均有影响,但各指标的影响程度及稳定性并不相同,公司规模及市净率指标对股票回报的影响较大,稳定性较强,市盈率的影响较小,稳定性较弱。这表明在中国A股市场上存在较为明显的"小公司效应",同时在预测股票回报时,市净率也是一个重要的变量,但投资者不能仅仅利用市盈率这一单一指标作为投资依据。     

股票市场流动性溢价的实证研究

资产流动性的高低是否影响资产的价格一直是资本市场理论研究的热点问题，也是投资者决策的重要理论依据之一。本文根据股票市场流动性溢价原理，选取换手率与Amivest流动比率作为股票流动性的衡量指标，采用LR两阶段截面回归方法与似无关回归（SUR）估计法，对上海股票市场的股票流动性与预期收益率的关系进行了实证研究。结果表明，上海股票市场存在显著的流动性溢价，换手率低或Amivest流动比率低，流动性较差的资产具有较高的预期收益。研究同时发现，上海股票市场具有很强的规模效应和价值效应。     

股票流动性对上市公司价值的影响研究

为了考察二级市场股票流动性对上市公司价值的影响,以2004~2009年间沪深两市A股股票分笔交易数据为样本,利用相对有效价差与托宾Q作为代理指标进行实证检验并加以分析。结果表明,股票二级市场流动性同上市公司价值之间具有显著的正相关关系。股票流动性提高,公司资本成本降低,经营业绩改善,上市公司价值提升。     

中国股市日内流动性效应分析——基于高频数据的流动性度量、特征及其影响因素

本文归纳了流动性刻画维度和度量指标,选取不同规模和价位股票的高频数据作样本,吸收Amivest流动性比率计算原理,设定价格对交易量变动的敏感性为流动性度量指标,分析股票日内交易特征和流动性影响因素。结果发现：日内模式价格变动呈仰卧“F”形,交易量呈仰卧“E”形,而非传统的“L”或“U”型;日内交易模式、股票规模和股票价位均影响着股票流动性;日内模式异动时间内,股票流动性差;大规模股票流动性强;高价股流动性差。     

我国上市公司股权结构与公司业绩实证

股权结构作为公司治理结构的基础和重要组成部分,其设置状况对公司投资效率具有一定的决定性作用。股权结构是指股东所持有公司股份的比例,它有两层含义：股权集中度和股权构成。刘怀珍,欧阳令南（2004）从股权制度安排、股票融资与投资行为之间关系出发进行研究得出：中国上市公司投资特征为＂效率悖论＂,     

Trading cost expectations: Evidence from S&P 500 index replacement stock announcements

This paper tests the effect on stock value of an expected change in future trading costs. The capitalized value of a reduction in trading costs is hypothesized to increase the stock value, a trading cost effect. Improved liquidity reduces trading costs. Inclusion as an S&P 500 Index replacement stock is an event hypothesized to increase liquidity. We use 114 observations between January 1, 1983 and October 12, 1989 of stocks added to the Index as replacements for stocks removed. The abnormal return of each stock is regressed against the ratio of the bidask spread to the price of the stock, the change in trading volume of the stock, and the open interest in the Index futures contracts at the close of the month prior to the replacement announcement. We find that the positive abnormal returns for replacement stocks are related to increased daily trading volume after inclusion in the Index. Further, the trading cost effect is proportional to percentage bid-ask spreads prior to inclusion. The trading cost effect increases as trading in derivatives of the Index increases. The volume and stock price changes after replacement are not transitory, indicating an improvement in liquidity. Three alternate hypotheses suggested in prior research to explain the abnormal returns for replacement stocks are tested. Testing each of the three models previously considered: price pressure, inelastic demand curves, and information, we find that none can be accepted with statistical confidence. The abnormal returns of Index replacement stocks are consistent with rational pricing of an anticipated reduction in future transaction costs. This anticipated reduction is capitalized in the value of the stock at the time of the replacement announcement. These results are consistent with a trading cost effect.     

Retail investors’ trading and stock market liquidity

The paper investigates the relation between retail investors’ participation in trading and aggregate stock market liquidity. The findings show a positive and significant relation between retail investors’ trading and stock market liquidity. Examination of the determinants of retail investors’ trading reveals that, on average, retail investors with more diversified trading activity tend to trade when liquidity is higher, the frequency of their arrival to the market is not affected by the level of liquidity, and retail investors are willing to trade at a lower liquidity level as sellers than as buyers. Moreover, retail investors’ trading does not create price noise at the aggregate market level. Overall, the evidence suggests that retail investors contribute to market quality.     

最小报价单位、价格水平与流动性——基于上海股市的实证研究

最小报价单位是证券市场交易机制设计的重要组成部分。与许多市场不同 ,我国证券市场采取单一的最小报价单位。本文利用上海股市的高频日内数据 ,对中国证券市场中最小报价单位对不同价格水平股票的流动性的影响进行了实证研究 ,研究结果表明适度提高高价股票的最小报价单位可能通过提高报价深度而促进这类股票的流动性。     

Day trading and stock price volatility

When an investor buys and sells the same stock on the same day, he is said to have made a day trade. Using the trading records of Finnish traders, this paper examines whether day trading is related to volatility of stock prices. I find a strong positive time-series relation between the number of day trades by individual investors and intraday volatility among heavily day traded stocks. This effect is robust after controlling for a previously documented volume–volatility relation. The result suggests that the joint hypothesis of price pressure and volatility induced day trading dominates the liquidity effects of day trading.     

Empirical evidence on the effects of delisting from the National Market System

This study analyzes empirical evidence related to changes in market value and liquidity characteristics of stocks, which are delisted from the National Market System (NMS) due to an elevation of NMS listing standards. Our results are thus relatively independent of the financial conditions of the firms prior to delisting. We document significant increase in bid-ask spreads and decrease in trading volume after delisting. A significant negative stock price reaction around the delisting announcement period is also observed. Both sets of findings suggest that delisting from NMS increases a firm’s cost of capital by adversely affecting the liquidity of its stock. (JEL: G14)     

Large price movements and short-lived changes in spreads,volume, and selling pressure

In this paper we examine changes in dollar and relative bid-ask spreads of stocks following large price movements. We investigate large increases and decreases separately and link our results to current market microstructure theories on trading activities and spreads. We also look at changes in volume and selling pressure to interpret the changes in trading activity. Our results show that the market reacts differently to price increases and decreases. For large price decreases, trading increases on the sell side even when spreads have increased. For large price increases, trading increases on the buy side during a period of higher spreads. However, the increases in dollar spreads and price pressure are most pronounced at the end of trading day. Our results are consistent with microstructure models that link trading activities and costs to the level of asymmetric information.     

股票交易的数学模型分析

股票投资要慎重决策,公司的基本面即公司的发展状况是股票价格的重要依据。用预测公司的每股利润的增长率来预测股价的未来走势,建立相关的数学模型,算出股价变动期望值与方差,依据数值的大小来决策买入卖出,这是较为可行的股票交易决策方法。同时也可参考成交量的变化来决策买入卖出的时机。     

交易量适合作为股价波动信息的代理变量吗?——来自中国沪深股市的证据

本文利用中国沪深股市日交易数据,采用多元GARCH模型从信息传递的角度进行实证研究,结果表明:股价对交易量具有显著的波动溢出效应,但交易量对股价的波动溢出效应不明显。这种波动的单向溢出说明在应对信息的冲击上股价比交易量能更快地做出反应,其后才通过波动溢出在交易量上得到反映,股价波动对成交量波动具有先导作用。因此,从波动冲击传导和信息传递的角度看,单纯地将交易量视为股价变动信息的代理变量还缺乏稳健的统计证据。     

Do size and unobservable company factors explain stock price reversals?

We use daily price data from the Egyptian stock market and a Loser portfolio of 20 IPOs from the late 1990s that experienced dramatic 1-day price falls in the period 2004 to 2007 to estimate a 2-way fixed effects model of CARs. Observable covariates are company size and turnover growth and unobservables company and period fixed effects. Our results provide evidence of significant price reversal over the first 40 post-event days. Firm size is negatively correlated with post-event CARs, consistently with the argument that small firms have a stronger tendency to price-reverse due to greater informational opacity. But permanent, unobservable company-specific factors, account for a much larger percentage of post-event variation in stock prices and indicate an underlying heterogeneity in investor responses to initial price falls not uncovered before in the literature. Strong negative company effects following a price fall are found to presage reinforcing ‘long term’ price falls and strong positive company effects to presage countervailing ‘long term’ price reversals. At the extremes these company effects are sufficiently large to suggest that a trading strategy based on them would be profitable.