借贷投资和资产价格泡沫:理论与实证分析

现代金融市场上普遍存在着信息不对称和借贷投资行为,以及由此带来的风险收益不对称和风险转移问题,这会造成资产价格膨胀从而形成泡沫。基于选择有代表性投资者的借贷投资活动为研究对象,通过引入贷款价值比(LTV)进一步扩展Allen-Gale模型,并用LTV的动态调整来说明金融市场上资产价格泡沫生成的内在机理及其影响,以及通过模拟分析后得出:利率不变时,LTV越大,资产价格泡沫程度越大;LTV不变时,利率越低,资产价格泡沫程度越大。因此,遏制资产价格泡沫的关键是降低LTV,提高利率。     

商业银行行为与资产市场泡沫--一个基于中国制度背景的均衡模型

资产市场均衡价格高于其真实价格的部分即为泡沫,泡沫破灭将导致财富幻觉的消失,进而造成需求萎缩、投资不足、经济增长放缓等不良后果.文章研究表明,制度缺陷将导致资产市场理性泡沫的存在.在资产市场配额供给、商业银行承担两类代理成本、央行实施价格管制、监管当局实施资产比例管理等制度背景下,存在私人利益和正的边际私人利益的银行家,倾向于向资产市场过度供给贷款,从而导致风险资产价格相对于银行家无私人利益时的均衡资产价格而言,系统性地被高估.在商业银行与银行监管当局仅根据风险资产最近成交价格预测银行贷款组合或贷款低押物未来价值这一信息结构下,一次交易中所形成的资产市场泡沫,可能会随着时间的延续而逐渐累积.     

基于投资者情绪的资本资产定价理论研究

笔者构建了基于投资者情绪的资产定价理论模型,就投资者情绪对风险资产定价有系统性的影响进行研究。研究发现股票均衡价格可以分解成理性部分和情绪部分,投资者情绪导致价格偏离内在价值并导致高的波动率和价格泡沫。基于信息的动态情绪资产定价模型和连续时间情绪资产定价模型,对以模糊数学为基础构建基于投资者情绪的行为投资组合,提供了可行的研究方向。     

基于进化博弈链结构的股票市场非理性泡沫测算问题研究

本文针对股市噪声不断累积,强化和排除的循环过程,基于股票市场对称进化博弈链结构模型,讨论了上海证券交易所正常情况下和极端情况下采用噪声交易策略比例的博弈进化过程和进化稳定策略,并将这个动态比例过程扩展到改进的DSSW模型中,据此测算出上证股市非理性泡沫大小.研究发现,在一定条件下,市场中的噪声交易者越多,风险资产价格非理性泡沫成分越大,波动越剧烈.本文的工作为股市泡沫的分析和测度提供了新的思路和工具.     

预算软约束、融资溢价与杠杆率——供给侧结构性改革的微观机理与经济效应研究

本文针对我国部分企业中存在的预算软约束问题及其造成价格扭曲、资源错配的现实背景,在金融加速器理论的基础上,首先建立嵌入预算软约束的金融加速器机制,通过企业与金融机构债务契约优化问题,得到预算软约束企业的融资溢价方程,阐述预算软约束造成价格扭曲及资源错配的内生机理。然后构建动态随机一般均衡模型,阐释供给侧结构性改革"三去一降一补"五大任务对经济变量的具体影响,并通过参数调整揭示供给侧结构性改革削弱预算软约束,增强宏观调控政策有效性以及促进长期经济增长的微观机理和经济效应,进而为推进供给侧结构性改革和经济长期可持续发展提供理论依据和政策建议。     

预算软约束对我国银行体系脆弱性影响的实证分析

文章运用自回归分布滞后模型,选择银行对非金融企业贷款额的变动衡量预算软约束导致的信贷膨胀程度,实证研究了预算软约束时我国银行体系脆弱性的影响.结果表明,银行体系的脆弱性受到自身滞后一期的影响显著.预算软约束当期变量与滞后一期变量对银行体系有显著影响,当期的预算软约束程度增加了银行体系的脆弱性,滞后一期的预算软约束程度减少了银行体系的脆弱性.     

声誉、软预算约束与混合所有制经济发展

本文以D-M模型为基础,构建了一个声誉条件下混合所有制投资软预算约束模型,探索软预算约束对混合所有制投资项目的影响.研究发现,在无声誉条件下,混合所有制投资项目存在逆向选择问题,是软预算约束的产物;将借贷双方声誉引入后,声誉对于硬化混合所有制投资软预算约束、抑制逆向选择的作用是毋庸置疑的.但声誉功能的发挥面临一些限制条件,制约了声誉在硬化软预算约束上的有效性,是制约中国混合所有制经济发展的障碍之一.对此,需要积极采取各种市场与非市场政策,努力培育成熟的市场经济.     

中国宏观杠杆率对房地产价格泡沫的非对称动态影响研究

本文从理论上分析资产价格泡沫与金融杠杆之间的定价关系,发现在违约概率为正的前提下,金融杠杆的上升会导致正向资产价格泡沫增大.为验证上述理论结果,本文采用NARDL模型实证分析了分部门宏观杠杆率对我国房地产价格泡沫的长、短期非对称影响.实证结果表明,首先,实体经济部门以及金融部门杠杆率的负向调整均会长期有效抑制房地产价格泡沫的持续膨胀,但"一刀切"的逆周期杠杆调整不利于房地产市场的长期稳定运行,因此应实行差异化的杠杆调控政策.其次,在长期可采用非金融企业部门向居民部门的杠杆转移来实现对房地产价格泡沫的温和平抑作用.再次,应有效、合理发挥中央政府杠杆的前瞻指引作用.同时,政策当局不应对地方政府施行强效去杠杆政策,应试图"熨平"地方政府债务波动以免引发局部房地产价格泡沫风险.最后,就金融部门而言,应对金融部门杠杆进行有效调控,谨防金融资产价格泡沫向房地产价格泡沫转移所引发的房地产市场泡沫风险.     

信贷扩张、资产价格泡沫及在中国的经验分析

资产价格泡沫源自信贷扩张,信贷扩张对资产价格的作用机制是借款人的风险转移行为.从经验证据上分析了我国信贷扩张对房地产价格存在的因果关系及商业银行中长期存在流动风险和结构不合理等问题.     

政策性负担与长期预算软约束

经济学家们很早就注意到了政策性负担对预算软约束的影响,然而现有的有关政策性负担的理论模型主要集中讨论政策性负担与企业补贴的关系,但企业补贴并不等于预算软约束。为此,本文首先建立了一个简单的三阶段动态博弈模型,在该框架下我们可以准确地定义预算软约束问题,并分析政策性负担对预算软约束的影响。然后,我们利用重复博弈的思想将本文的基本模型动态化,建立了长期预算软约束的基本理论框架,这在现有的预算软约束文献中是不多见的,有助于更加全面地考察影响政策性负担、预算软约束和道德风险问题的各种因素。本文的主要结论是,政策性负担是导致企业出现预算软约束问题的重要根源之一,但如果政府和企业之间的博弈可以重复进行,预算软约束问题能够得到有效缓解。     

Bubbles as payoffs at infinity

Summary We define rational bubbles to be securities with payoffs occurring in the infinitely distant future and investigate the behavior of bubbles values. We extend our analysis to a setting of uncertainty. In an infinite horizon arbitrage-free model of asset prices, we interpret the money market account as the value of a particular bubble; a similar interpretation holds for other assets related to the state-price deflator and to payoffs on bonds maturing in the distant future. We present three applications of this characterization of bubbles.This paper was circulated under the title Stochastic bubbles in Markov economies. We acknowledge with gratitude numerous conversations with Mark Fisher, the editorial advice of David Levine and the useful comments of anonymous referees. This paper should not be interpreted as reflecting the views of the Board of Governors of the Federal Reserve System or its staff.     

Asset bubbles,banking stability and economic growth

This paper examines the relationships between the asset bubble and the banking stability from both theoretical and empirical perspectives. The theoretical analysis demonstrates that the moral hazard caused by the deposit insurance and limited liability might facilitate the banks to hold bubble assets for the purpose of risk premium. Meanwhile the supervisory intensity, leverage ratio and credit spread provide the conditions for banks to hold bubble assets through their effects on risk premium. Once the banks hold the bubble assets, their stability will deteriorate because of four types of effects, namely internal leverage, cash withdrawal, credit friction and network effects. This paper also utilizes the BMA-PVAR model to test the theoretical findings by employing the data from 26 representative economies for a period between 2000 and 2014. The empirical evidences are consistent with the theoretical findings that the equity bubbles will lower the banking stability. The empirical evidences also suggest that the banking instability will be detrimental to the economic growth.     

中国股市的理性泡沫

传统理论通常把证券市场的泡沫与投资者的非理性行为混为一谈。近期的研究却表明在一个完全理性的市场中 ,泡沫依然可以出现。本文首先对我国证券市场存在理性泡沫的可能性提出多种理论解释 ,认为下列原因导致了我国证券市场泡沫的存在 :( 1 )上市审批制 ;( 2 )可供投资的证券种类少 ;( 3 )政府的托市行为 ;( 4)卖空机制的缺乏 ;( 5)套利机制缺乏有效性 ;( 6)上市公司很少分红 ,投资者买卖股票只是为了获得买卖差价。其次 ,我们通过分析所得的结果 ,提出应对理性泡沫的政策措施。     

Soft landing in a Markov-switching economy

We analyse the monetary policy implications of boom–bust cycles in asset prices using a Markov-switching rational expectations model. In our simulations, when a bubble bursts, the Taylor rule fails to achieve a soft landing, contrary to the optimal policy.     

论投机性泡沫的内生性——基于一个模拟投机交易过程的经验模型

通过一个简约的模拟投机交易的经验模型,阐述了投机性泡沫是投机者对资产价格预期的一种自我实现①,它内生于投机者对资产价格进行无约束的套利交易过程中,其内在机制是交易数量的加速膨胀和预期的资产价格增长的相互作用。并据此认为政府管理部门首先应根据经济宏观和微观运行状况,结合资产的特点,为资产价格确立一个目标区域,并运用结构性的货币政策、延展交易资产的持有时间以及征收交易税等手段对资产价格进行有效管理,以防范投机性泡沫的形成和扩展。     

“Overreaction” of Asset Prices in General Equilibrium

We attempt to explain the overreaction of asset prices to movements in short-term interest rates, dividends, and asset supplies. The key element of our explanation is a margin constraint that traders face which limits their leverage to a fraction of the value of their assets. Traders may lever themselves, furthermore, either directly by borrowing short term or indirectly by engaging in futures and options trading, so that the scenario is relevant to contemporary financial markets. When some shock pushes asset prices to a low enough level at which the margin constraint binds, traders are forced to liquidate assets. This drives asset prices below what they would be with frictionless markets. Also, a shock which simply increases the likelihood that the margin constraint will bind can have a very similar effect on asset prices. We construct a general equilibrium model with margin constrained traders and derive some qualitative properties of asset prices. We present an analytical solution for a deterministic version of the model and a simple numerical computation of the stochastic version.Journal of Economic LiteratureClassification Numbers: G1, E0.     

Information Markets and the Comovement of Asset Prices

Traditional asset pricing models predict that covariance between prices of different assets should be lower than what we observe in the data. This paper introduces markets for information that generate high price covariance within a rational expectations framework. When information is costly, rational investors only buy information about a subset of the assets. Because information production has high fixed costs, competitive producers charge more for low-demand information than for high-demand information. The low price of high-demand information makes investors want to purchase the same information that others are purchasing. When investors price assets using a common subset of information, news about one asset affects the other assets' prices; asset prices comove. The cross-sectional and time-series properties of comovement are consistent with this explanation.     

Bubbles and Crises

In recent financial crises a bubble, in which asset prices rise, is followed by a collapse and widespread default. Bubbles are caused by agency relationships in the banking sector. Investors use money borrowed from banks to invest in risky assets, which are relatively attractive because investors can avoid losses in low payoff states by defaulting on the loan. This risk shifting leads investors to bid up the asset prices. Risk can originate in both the real and financial sectors. Financial fragility occurs when positive credit expansion is insufficient to prevent a crisis.     

Bubbles and rationality in bitcoin

Periodically collapsing rational bubbles model speculative demand in asset markets. The price and quantity of bitcoin are integrated of different orders, which is evidence of a bubble. Cointegration tests that allow for the potential presence of such bubbles with alternative proxies for fundamentals cannot reject a bubble in bitcoin.