Efficient portfolio is a portfolio that yields maximum expected return given a level of risk or has minimum level of risk given a level of expected return.However,the optimal portfolios seem not being as efficient as intended.Especially during financial crisis period.optimal portfolio is not an optimal investment as it does not yield maximum return given a specific level of risk,vice and versa.One possible explanion for an unimpressive performance of the seemingly efficient portfolio is incorrectness in parameter estimates called"estimation risk in parameter estimates".Five different estimating strategies are employed to explore ex post portfolio performance when estimation risk is incorporated.These strategies are traditional mean-variance(EV),Adjusted Beta(AB) approach,Capital Asset Pricing Model(CAPM),Single Index Model(SIM), and Single Index Model incorporating shrikage Bayesian factor namely Bayesian Single Index Model(BSIM).Among the five alternative strategies,shrinkage estimators incorporating the single index model outperforms other traditional portfolio selection strategies.Allowing for asset mispricing and applying Bayesian shrinkage adjusted factor to each asset's alpha,a single factor namely excess market return is adequate in alleviating estimation uncertainty. JEL：G320

We document the market response to an unexpected announcement of proposed sales of government-owned shares in China. In contrast to the “privatization premium” found in earlier work, we find a negative effect of government ownership on returns at the announcement date and a symmetric positive effect in response to the announced cancellation of the government sell-off. We argue that this results from the absence of a Chinese political transition to accompany economic reforms, so that the positive effects on profits of political ties through government ownership outweigh the potential efficiency costs of government shareholdings. Companies with former government officials in management have positive abnormal returns, suggesting that personal ties can substitute for the benefits of government ownership. In both cases, we may rule out explanations based on a supply effect of the share sales. We further find that the “privatization discount” is higher for firms located in Special Economic Zones, where local government discretionary authority is highest, And that companies with relatively high welfare payments to employees, which presumably would fall with privatization, benefit disproportionately from the privatization announcement.

企业作为自主创新的主体，其R&D投入可能带来公司价值的提升，并反映到股票预期收益即股票市价当中，本文拟从实证的角度对这一问题展开研究。本文以生物制药行业上市公司为样本，通过对Fama-French的三因素模型改进基础上，采用截面回归分析方法，探讨企业R&D密度与股票收益的相关性，得出R&D密度与股票收益不仅呈显著正相关关系，而且具有期性，但R&D活动偏重短期效益，缺乏连续性。最后，对本文实证结果的形成原因进行了解释，针对R&D投资中存在的不足，提出了改进建议。

本文以Ohlson模型考察2002-2007年A股亏损公司定价问题。针对亏损公司盈余与权 益价值负相关这一异常现象，我们通过将政府补贴、成长性、研发支出、负债融资信息引入定价 模型，发现政府补贴、成长性和负债因素能够有效改善模型，消除了盈余与权益价值显著负相关 的异常现象，改善了定价模型的效果。通过规模和净利润两个维度对亏损公司的进一步分类，我 们发现从净利润维度来看，政府向那些更容易通过非经常项目扭亏的公司提供了更多财政补贴， 并且政府补贴与净利润为正公司的权益价值显著负相关，与净利润为负公司的权益价值不存在显 著相关关系；从规模维度来看，上述现象在小公司样本更加明显。

With the expansion of multinational corporations (MNCs), the alarming upsurge in widely publicized and notable corporate scandals involvingMNCs in emerging markets has begun to draw both academic and managerial attention to look beyond home market practices to the pressing concern of CSR in emerging markets. Previous studies on CSR have focused primarily on Western markets, reserving limited discussions in addressing the issue of MNC attitudes and CSR practices in their emerging host markets abroad. Despite this incongruity in academic response to CSR in emerging markets, managers of multinational companies continue to face mounting and most often conflicting pressures to weigh among multiple strategic CSR responses in emerging markets. Such a task is often further complicated by the complexity of varying business norms and standards, regulatory environments, and stakeholder demands for CSR across national boundaries. With such a challenge in mind, I attempt to examine the explanatory factors in leading MNCs, otherwise recognized for accountability and integrity in their home markets, to employ inconsistent or negligent practices under CSR pressure in Chinese emerging economy. Preliminary findings reveal that discrepancies exist in how MNCs perform in CSR in home countries versus in host countries. While MNCs do have much to improve, the institutional environment in the emerging market, including the legal framework and the ethical culture, also needs to be improved by the host country governments, the industry associations, and local firms. Meanwhile, media interest and journalists, NGOs, third party monitors, industry stakeholders as well as consumer advocacy groups can raise the visibility of MNC’s contradictory practices between their origin nations and countries with emerging economies and offer the pressures and incentives for MNCs to amend their ethical shortcomings. This article also suggests implications for both theory and practice.

由于受国内外多种因素共同影响，期货价格在短时间内变动较大，为准确拟合与预测期货价格，本文根据期货价格的行为特征，提出一个n因素的仿射期限结构模型，并基于卡尔曼滤波和极大似然法，以沪铜日结算价的面板数据为样本对期货价格的期限结构进行实证分析.结果表明，该仿射模型对沪铜是适用的，而且模型中因素数目越多，模型拟合与预测能力越强，其中，二因素的仿射模型可以较为准确地模拟期货价格的期限结构,三因素的仿射模型可以较为准确地模拟和预测期货价格的期限结构.

The purpose of this paper is to investigate the certification and monitoring roles played by underwriters in IPO earnings management. Prior studies show that IPO issuers have incentives to employ opportunistic earnings management to enhance initial firm values. However, the certification role of underwriters has been largely overlooked. We argue that there is a negative relation between underwriter reputation and IPO earnings management. Moreover, we think that underwriters have strong incentives to continue providing monitoring to the firms they take public due to the lucrative business relationships. We thus hypothesize that there is a positive relation between underwriter reputation and post-IPO firm operating performance. Using a sample of 367 IPOs, we obtain results consistent with our hypotheses. We find that IPOs underwritten by lower-reputation underwriters have more initial discretionary accruals and higher initial firm values, indicating there is a significantly negative relation between IPO earnings management and underwriter reputation. We also find that the post-IPO operating performance of IPOs is significantly and positively related to underwriter reputation. For the robustness test, we consider the possibility that IPO earnings management and the choice of underwriters are endogenously determined. An instrumental variable two-stage least squares regression and a weighted least squares regression confirm the robustness of our results.

This paper tests the relation between large shareholders and firm value using a recent reform in China’s equity market. The reform eliminated the discrepancy between large shareholders’ voting rights and cash-flow rights. The paper finds that large shareholders expropriate less through related party transactions after the reform when the discrepancy between their voting rights and cash-flow rights prior to the reform was larger. It also finds that minority shareholders gain from the reform: firms earn higher excess returns around the reform announcements when the discrepancy was larger. Finally, it provides the evidence of efficiency gains associated with the reform. The paper concludes that the discrepancy between large shareholders’ voting rights and cash-flow rights can lead to efficiency losses.

The article chooses 453 non-financia l listed companies for the regression analysis to study the the ma in factors affecting China listed companies’ cash hold ings, using net increase in cash and cash equiva lents assets ratio(NCAR) as the change index of listed companies ’ cash hold ings, reflects both the change direction and degree of cash hold ings. According to the comprehensive analysis we find: the avera ge cash and equiva lents was increase from 2000 to 2007, and the avera ge NCAR was increasing since 2004; the avera ge NCAR of the non-sta te-controlled listed companies is higher tha n that of state-controlled ones, and the ma ximum and minimum of NCAR are all occurred in state-controlled listed companies; there exists a much significa nt correla tion between cash flow assets ratio and NCAR, the investment opportunities and the nature of domina nt stockholder have significa nt positive effects on NCAR ; and the enterprise size, profitability, the first majority shareholder sharehold ing ratio, executives sharehold ing ratio, concentration ration all have nonsignifica nt effects on NCAR.

This paper studies the optimal contracting problem between shareholders and the agent in a general cash-ow setup, and offers a framework to quantitatively assess the impact of agency problems. Under the structural model of capital structure studied in Leland (1994), we solve the optimal employment contract explicitly, and nd that debt-overhang lowers the optimal leverage. Consistent with the data, our model delivers a negative relation between pay-performance sensitivity and rm size, and the interaction between debt-overhang and agency issue leads smaller rms to take less leverage relative to their larger peers. During nancial distress, a rm’s cash-ow becomes more sensitive to underlying performance shocks due to debt-overhang. We also consider the possibility of debt covenants to alleviate the debt-hang problem.