DYNAMIC PORTFOLIO OPTIMIZATION WITH A DEFAULTABLE SECURITY AND REGIME‐SWITCHING

We consider a portfolio optimization problem in a defaultable market with finitely‐many economical regimes, where the investor can dynamically allocate her wealth among a defaultable bond, a stock, and a money market account. The market coefficients are assumed to depend on the market regime in place, which is modeled by a finite state continuous time Markov process. By separating the utility maximization problem into a predefault and postdefault component, we deduce two coupled Hamilton–Jacobi–Bellman equations for the post‐ and predefault optimal value functions, and show a novel verification theorem for their solutions. We obtain explicit constructions of value functions and investment strategies for investors with logarithmic and Constant Relative Risk Aversion utilities, and provide a precise characterization of the directionality of the bond investment strategies in terms of corporate returns, forward rates, and expected recovery at default. We illustrate the dependence of the optimal strategies on time, losses given default, and risk aversion level of the investor through a detailed economic and numerical analysis.     

极端市态中基金申购赎回行为研究——基于中国开放式股票型基金的分析

自2007年初至2008年末,我国证券市场经历了一轮明显的牛熊市转换。对这一时段的基金申购赎回行为进行研究发现：在极端市态中,开放式股票型基金申购、赎回数量的巨额差异背后,存在着中购、赎回行为影响因素的巨大差异。通过对这些差异的研究,可以为深入了解投资者的心理,预测和指导未来投资者行为提供很好的帮助。研究结果还表明：我国基金的个人投资者正在走向成熟;基金的机构投资者较为理性,其交易行为趋向长期化。     

OPTIMAL INVESTMENT STRATEGIES FOR CONTROLLING DRAWDOWNS

We analyze the optimal risky investment policy for an investor who, at each point in time, wants to lose no more than a fixed percentage of the maximum value his wealth has achieved up to that time. In particular, if M _t is the maximum level of wealth W attained on or before time t , then the constraint imposed on his portfolio choice is that W_tα M _t, where α is an exogenous number betweenα O and 1. We show that, for constant relative risk aversion utility functions, the optimal policy involves an investment in risky assets at time t in proportion to the "surplus" W _t - α M _t. the optimal policy may appear similar to the constant-proportion portfolio insurance policy analyzed in Black and Perold (1987) and Grossman and Vila (1989). However, in those papers, the investor keeps his wealth above a nonstochastic floor F instead of a stochastic floor α M _t. the stochastic character of the floor studied here has interesting effects on the investment policy in states of nature when wealth is at an all-time high; i.e., when Wt = M _t. It can be shown that at W _t= M _t, α M _t is expected to grow at a faster rate than W _t, and therefore the investment in the risky asset can be expected to fall. We also show that the investment in the risky asset can be expected to rise when W _t is close to α M _t. We conjecture that in an equilibrium model the stochastic character of the floor creates "resistance" levels as the market approaches an all-time high (because of the reluctance of investors to take more risk when W _t= M _t).     

OPTIMAL CONSUMPTION AND PORTFOLIO DECISIONS WITH PARTIALLY OBSERVED REAL PRICES

We consider optimal consumption and portfolio investment problems of an investor who is interested in maximizing his utilities from consumption and terminal wealth subject to a random inflation in the consumption basket price over time. We consider two cases: (i) when the investor observes the basket price and (ii) when he receives only noisy observations on the basket price. We derive the optimal policies and show that a modified Mutual Fund Theorem consisting of three funds holds in both cases. The compositions of the funds in the two cases are the same, but in general the investor's allocations of his wealth into these funds will differ. However, in the particular case when the investor has constant relative risk-aversion (CRRA) utility, his optimal investment allocations into these funds are also the same in both cases.     

Testing the Tracking Efficiency of Commodity Exchange Traded Funds (ETFs) across the Bearish and Bullish Market Regimes: Evidence from Indian Gold ETFs

Commodity exchange traded funds (ETFs) help investors gain exposure to the underlying commodity in digital form. The present article attempts to examine the performance characteristics of 12 gold ETFs in India across the bear and bull markets. ETFs’ sensitivity to their underlying asset (gold prices) is observed to be lower during the bearish market regime, and, as such, the tracking error is found to be higher during the bearish market regime. Further, volume is reported to bear a significant positive impact on the tracking ability of ETFs whereas volatility and pricing deviation are found to negatively impact the tracking ability of ETFs.     

我国股市过度投机下个体证券投资者行为分析

过度投机是我国股市的现状,而研究这种状况下投资者采取何种投资策略,对于其能否克服投机行为带来的风险,并进而利用其他投资者的行为来获取收益至关重要。文章从行为金融的角度去研究个体投资者的交易行为,深入考察了中国个体证券投资者行为的主要特点,并分析其行为的决定因素。在此基础上提出个体证券投资者在交易中应该采取的有效投资策略。     

Who should sell stocks?

Never selling stocks is optimal for investors with a long horizon and a realistic range of preference and market parameters, if relative risk aversion, investment opportunities, proportional transaction costs, and dividend yields are constant. Such investors should buy stocks when their portfolio weight is too low and otherwise hold them, letting dividends rebalance to cash over time rather than selling. With capital gains taxes, this policy outperforms both static buy‐and‐hold and dynamic rebalancing strategies that account for transaction costs. Selling stocks becomes optimal if either their target weight is low or intermediate consumption is substantial.     

MONOTONICITY PROPERTIES OF OPTIMAL INVESTMENT STRATEGIES FOR LOG-BROWNIAN ASSET PRICES

Consider the geometric Brownian motion market model and an investor who strives to maximize expected utility from terminal wealth. If the investor's relative risk aversion is an increasing function of wealth, the main result in this paper proves that the optimal demand in terms of the total wealth invested in a given risky portfolio at any date is decreasing in absolute value with wealth. The proof depends on the functional form of the Brunn–Minkowski inequality due to Prékopa.     

Does Sustainability Investment Provide Adaptive Resilience to Ethical Investors? Evidence from Spain

Although sustainable and responsible investment (SRI) has quite recently become a hot research topic, scarcely any systematic research has been paid to the performance of this non-conventional approach to investment during the financial crisis that emerged in mid-2008 when the resilience of the financial markets was sorely tested. Such real-world resilience in practice is the subject of the current research which tests whether environmental, social and governance screens provides ethical investors with adaptive resilience in bull and bear market conditions by focussing on the SRI equity index of one of the most active markets in Europe in terms of ethical investment, the FTSE4Good-Ibex in Spain. Multivariate Generalized Autoregressive Conditional Heteroskedasticity (M-GARCH) analysis indicates that ethical investors in the equity market examined with evidence that greater resilience in severe business cycle shocks could be attributable to SRI by companies. Although limited to a single country study, the results have implications for investors seeking resilience in crisis: when individual values and beliefs towards sustainability tie with personal investment strategy, the end result is adaptive financial resilience, social well-being and environmental defence.     

相对财富与股票溢价之谜

Mehra和Prescott( 1 985 )提出著名的股票溢价之谜 (EquityPremiumPuzzle) :合理的相对风险规避系数 ,不能解释美国S&P5 0 0指数的收益率为什么比无风险债券的收益率高出 6个百分点。本文提出了一个基于相对财富的资产定价模型 ,其中代表性投资者的效用函数不但依赖于消费 ,还依赖于投资者的绝对财富 ,及社会平均财富。本文使用该模型 ,解释了股票溢价之谜。     

Dividend policy and capital structure of a defaultable firm

Default risk significantly affects the corporate policies of a firm. We develop a model in which a limited liability entity subject to default at an exponential random time jointly sets its dividend policy and capital structure to maximize the expected lifetime utility from consumption of risk‐averse equity investors. We give a complete characterization of the solution to the singular stochastic control problem. The optimal policy involves paying dividends to keep the ratio of firm's equity value to investors' wealth below a critical threshold. Dividend payout acts as a precautionary channel to transfer wealth from the firm to investors for mitigation of losses in the event of default. Higher the default risk, more aggressively the firm leverages and pays dividends.     

Optimal make–take fees for market making regulation

We address the mechanism design problem of an exchange setting suitable make– take fees to attract liquidity on its platform. Using a principal–agent approach, we provide the optimal compensation scheme of a market maker in quasi‐explicit form. This contract depends essentially on the market maker inventory trajectory and on the volatility of the asset. We also provide the optimal quotes that should be displayed by the market maker. The simplicity of our formulas allows us to analyze in details the effects of optimal contracting with an exchange, compared to a situation without contract. We show in particular that it improves liquidity and reduces trading costs for investors. We extend our study to an oligopoly of symmetric exchanges and we study the impact of such common agency policy on the system.     

风格漂移与基金绩效

基于收益率的风格分析模型,对国内36支开放式基金进行动态分析,将基金的实际投资风格和宣称的投资风格进行比较。研究发现绝大多数的基金在此研究期间发生了"风格漂移"现象,牛市行情中发生"风格漂移"的基金绩效要优于固守宣称风格的基金绩效,熊市行情中发生"风格漂移"的基金绩效要低于未发生"风格漂移"的基金绩效。     

LONG HORIZONS,HIGH RISK AVERSION,AND ENDOGENOUS SPREADS

For an investor with constant absolute risk aversion and a long horizon, who trades in a market with constant investment opportunities and small proportional transaction costs, we obtain explicitly the optimal investment policy, its implied welfare, liquidity premium, and trading volume. We identify these quantities as the limits of their isoelastic counterparts for high levels of risk aversion. The results are robust with respect to finite horizons, and extend to multiple uncorrelated risky assets. In this setting, we study a Stackelberg equilibrium, led by a risk‐neutral, monopolistic market maker who sets the spread as to maximize profits. The resulting endogenous spread depends on investment opportunities only, and is of the order of a few percentage points for realistic parameter values.     

DISUTILITY, OPTIMAL RETIREMENT, AND PORTFOLIO SELECTION

We study the optimal retirement and consumption/investment choice of an infinitely-lived economic agent with a time-separable von Neumann–Morgenstern utility. A particular aspect of our problem is that the agent has a retirement option. Before retirement the agent receives labor income but suffers a utility loss from labor. By retiring, he avoids the utility loss but gives up labor income. We show that the agent retires optimally if his wealth exceeds a certain critical level. We also show that the agent consumes less and invests more in risky assets when he has an option to retire than he would in the absence of such an option.
An explicit solution can be provided by solving a free boundary value problem. In particular, the critical wealth level and the optimal consumption and portfolio policy are provided in explicit forms.     

Currency risk and the dynamics of German investors entry and exit in Russia

Using a complete manually collected set of 3435 Russian firms with German capital in 2003–2020, we examine the effect of currency risk on the dynamics of German investors' entry and exit into the Russian market via foreign direct investment. We document that German investors were relatively tolerant towards currency risk before 2014, and became highly sensitive post 2014. We conclude that, along with geopolitical factors, the free floating exchange rate regime adopted by the Central Bank of Russia in 2014 affected the incentives of German investors. We discuss various mechanisms to explain these findings.     

Did Investors Herd during the Financial Crisis? Evidence from the US Financial Industry

We examine the herding behavior of investors in the US financial industry, especially commercial banks, S&Ls, investment and insurance firms during global financial crisis of 2008 towards own sub‐sector and market consensus using augmented cross sectional absolute deviation of returns (CSAD) model. After distinguishing between fundamental and non‐fundamental information, we find a greater influence of global financial crisis on spurious herding for commercial and investment banks, and such herding increases in the down market and with conditional volatility of returns, but adverse herding is prevalent among investors during normal period in response to fundamental information. We also find that herding intensity on fundamental information is relatively high with market consensus for all financial institutions except insurance firms in high volatility regime, and intentional herding is only significant and limited to S&Ls and investment banks in high volatility regime. Our findings suggest limited spillover effects of herding when investors face non‐fundamental information.     

基于经济增长的中国最优消费规模:1978—2006

中国长期实行"重投资、轻消费"的政策,消费率一直偏低。以限制消费为代价的经济增长不仅无法实现社会福利最大化和居民效用最大化,而且也是不可持续的。消费不足导致经济增长乏力,然而消费过度会导致投资不足从而阻碍经济增长,因此经济中存在最优的消费规模。在检验消费规模和经济增长关系的基础上,建立消费的内生增长模型,利用1978—2006年间29年的经验数据,求得中国消费率的最优值为66.46%,据以提出扩大消费以扩大内需、促进经济增长的政策建议。     

PORTFOLIO OPTIMIZATION WITH DOWNSIDE CONSTRAINTS

We consider the portfolio optimization problem for an investor whose consumption rate process and terminal wealth are subject to downside constraints. In the standard financial market model that consists of d risky assets and one riskless asset, we assume that the riskless asset earns a constant instantaneous rate of interest,   r > 0  , and that the risky assets are geometric Brownian motions. The optimal portfolio policy for a wide scale of utility functions is derived explicitly. The gradient operator and the Clark–Ocone formula in Malliavin calculus are used in the derivation of this policy. We show how Malliavin calculus approach can help us get around certain difficulties that arise in using the classical "delta hedging" approach.