A model of optimal portfolio selection under liquidity risk and price impact

We study a financial model with one risk-free and one risky asset subject to liquidity risk and price impact. In this market, an investor may transfer funds between the two assets at any discrete time. Each purchase or sale policy decision affects the rice of the risky asset and incurs some fixed transaction cost. The objective is to maximize the expected utility from terminal liquidation value over a finite horizon and subject to a solvency constraint. This is formulated as an impulse control problem under state constraints and we characterize the value function as the unique constrained viscosity solution to the associated quasi-variational Hamilton–Jacobi–Bellman inequality. We would like to thank Mihail Zervos for useful discussions.     

Optimal student loans and graduate tax under moral hazard and adverse selection

We characterize the set of second‐best “menus” of student‐loan contracts in an economy with risky labor‐market outcomes, adverse selection, moral hazard, and risk aversion. We combine student loans with optimal income taxation. Second‐best optima provide incomplete insurance because of moral hazard. Optimal repayments must be income contingent, or the income tax must comprise a graduate tax. Individuals are ex ante unequal because of differing probabilities of success, and ex post unequal, because taxation trades off incentives and redistribution. In addition, second‐best optima exhibit an interim equalization property: the poststudy but prework expected utilities of newly graduated student types must be equal.     

Risk allocation under liquidity constraints

Risk allocation games are cooperative games that are used to attribute the risk of a financial entity to its divisions. In this paper, we extend the literature on risk allocation games by incorporating liquidity considerations. A liquidity policy specifies state-dependent liquidity requirements that a portfolio should obey. To comply with the liquidity policy, a financial entity may have to liquidate part of its assets, which is costly.The definition of a risk allocation game under liquidity constraints is not straightforward, since the presence of a liquidity policy leads to externalities. We argue that the standard worst case approach should not be used here and present an alternative definition. We show that the resulting class of transferable utility games coincides with the class of totally balanced games. It follows from our results that also when taking liquidity considerations into account there is always a stable way to allocate risk.     

Optimal liquidation under stochastic liquidity

We solve explicitly a two-dimensional singular control problem of finite fuel type for an infinite time horizon. The problem stems from the optimal liquidation of an asset position in a financial market with multiplicative and transient price impact. Liquidity is stochastic in that the volume effect process, which determines the intertemporal resilience of the market in the spirit of Predoiu et al. (SIAM J. Financ. Math. 2:183–212, 2011), is taken to be stochastic, being driven by its own random noise. The optimal control is obtained as the local time of a diffusion process reflected at a non-constant free boundary. To solve the HJB variational inequality and prove optimality, we need a combination of probabilistic arguments and calculus of variations methods, involving Laplace transforms of inverse local times for diffusions reflected at elastic boundaries.     

Redistributive taxation and social insurance under adverse selection in the insurance market

This paper extends the analysis of optimal income taxation under uncertainty studied by Cremer and Pestieau (International Tax and Public Finance, 3, 281–295, 1996). We introduce asymmetric information in the insurance market whereby private insurance companies cannot identify the risk probability of the agents, and we examine its effect on public policy. We consider the separating equilibrium of Rothschild and Stiglitz (Quarterly Journal of Economics, 90, 629–649, 1976) and Riley (Econometrica, 47, 331–359, 1979) where the low risk agent is only partially insured. The presence of the distortion in the insurance market changes the affinity of labor, and in some cases, we show that the scope of redistribution and the resulting social welfare are higher under asymmetric information than under full information. We also show that the increase in social insurance affects the utility and labor incentive of the low risk type by relaxing the self-selection constraint in the insurance market. The policy implications of the redistributive taxation and social insurance are analytically and numerically examined.      

Productivity and liquidity management under costly financing

We explore theoretically and empirically the relationship between firm productivity and liquidity management in the presence of financial frictions. We build a dynamic investment model and show that, counter to basic economic intuition, more productive firms could demand less capital assets and hold more liquid assets compared to less productive firms when financing costs are sufficiently high. We empirically test this prediction using a comprehensive dataset of Chinese manufacturers and find that more productive firms indeed hold less capital and more cash. We do not, however, observe this for US manufacturers. Our study suggests a larger capital misallocation problem in markets with significant financing frictions than previously documented.     

Corporate liquidity and dividend policy under uncertainty

We examine optimal liquidity (retained earnings) and dividend choice incorporating debt financing with risk of default and bankruptcy costs as well as growth options under revenue uncertainty. We revisit the conditions for dividend policy irrelevancy and the broader role of retained earnings and dividends. Retained earnings have a net positive impact on firm value in the presence of growth options, high external financing costs and low default risk. High levels of retained earnings enhance debt capacity but have a negative effect on equity value due to the likelihood of losing accumulated cash balances in case of default, unless offset by high external financing costs. Opposite directional effects of retained earnings on equity and debt create a U-shaped relation with firm value. The framework is extended to analyze management-shareholder conflicts, demonstrating that managers accumulate higher than optimal cash.     

Corporate liquidity and dividend policy under uncertainty

We examine optimal liquidity (retained earnings) and dividend choice incorporating debt financing with risk of default and bankruptcy costs as well as growth options under revenue uncertainty. We revisit the conditions for dividend policy irrelevancy and the broader role of retained earnings and dividends. Retained earnings have a net positive impact on firm value in the presence of growth options, high external financing costs and low default risk. High levels of retained earnings enhance debt capacity but have a negative effect on equity value due to the likelihood of losing accumulated cash balances in case of default, unless offset by high external financing costs. Opposite directional effects of retained earnings on equity and debt create a U-shaped relation with firm value. The framework is extended to analyze management-shareholder conflicts, demonstrating that managers accumulate higher than optimal cash.     

Currency hedging for multinationals under liquidity constraints

This paper examines the impact of liquidity risk on the behavior of a risk-averse multinational firm (MNF) under exchange rate uncertainty in a two-period dynamic setting. The MNF has operations domiciled in the home country and in a foreign country, each of which produces a single homogeneous good to be sold in the home and foreign markets. To hedge the exchange rate risk, the MNF has access to one-period currency futures and option contracts in each period. The MNF is liquidity constrained in that it is obliged to terminate its risk management program in the second period whenever the net loss due to its first-period hedge position exceeds a predetermined threshold level. We show that the MNF optimally sells less (more) and produces more (less) in the foreign (home) country in response to the imposition of the liquidity constraint. We show further that the liquidity constrained MNF optimally uses the currency option contracts in the first period for hedging purposes in general, and opts for a long option position if its utility function is quadratic in particular.     

Investment timing and optimal capital structure under liquidity risk

Deterioration in debt market liquidity reduces debt values and affects firms' decisions. Considering such risk, we develop an investment timing model and obtain analytic solutions. We carry out a comprehensive analysis in optimal financing, default, and investment strategies, and stockholder–bondholder conflicts. Our model explains stylized facts and replicates empirical findings in credit spreads. We obtain six new insights for decision makers. We propose a ‘new trade-off theory’ for optimal capital structure, a new tax effect, and new explanations of ‘debt conservatism puzzle’ and ‘zero-leverage puzzle’. Failure in recognizing liquidity risk results in substantially over-leveraging, early bankruptcy or investment, overpriced options, and undervalued coupons and credit spreads. In addition, agency costs are surprisingly small for a high liquidity risk or a low project risk. Interestingly, the risk shifting incentive and debt overhang problem decrease with liquidity risk under moderate tax rates while they increase under high tax rates.     

Managing longevity risk under adverse selection: the influence of policyholder age and contract duration

In recent years, the rising life expectancy in almost all industrialized countries has led to an increasing demand by life insurers for possibilities to hedge longevity risk. Two of the most prominent alternative risk management instruments in this regard are the transfer of longevity risk to the capital market, e.g. through the purchase of mortality contingent bonds, and natural hedging, i.e. hedging longevity risk through portfolio composition. In this paper, we study the effectiveness of these risk management instruments under adverse selection, which here refers to the difference between annuitant mortality and the mortality of the population as a whole. Special emphasis is thereby placed on analyzing the impact of policyholders’ age at contract inception and contract duration on the effectiveness of risk management.     

Reinsurance contract design with adverse selection

ABSTRACT

In light of the richness of their structures in connection with practical implementation, we follow the seminal works in economics to use the principal–agent (multidimensional screening) models to study a monopolistic reinsurance market with adverse selection; instead of adopting the classical expected utility paradigm, the novelty of our present work is to model the risk assessment of each insurer (agent) by his value-at-risk at his own chosen risk tolerance level consistent with Solvency II. Under information asymmetry, the reinsurer (principal) aims to maximize his average profit by designing an optimal policy provision (menu) of ‘shirt-fit’ reinsurance contracts for every insurer from one of the two groups with hidden characteristics. Our results show that a quota-share component, on the top of simple stop-loss, is very crucial for mitigating asymmetric information from the insurers to the reinsurer.     

Option hedging for small investors under liquidity costs

Following the framework of Çetin et al. (Finance Stoch. 8:311–341, 2004), we study the problem of super-replication in the presence of liquidity costs under additional restrictions on the gamma of the hedging strategies in a generalized Black–Scholes economy. We find that the minimal super-replication price is different from the one suggested by the Black–Scholes formula and is the unique viscosity solution of the associated dynamic programming equation. This is in contrast with the results of Çetin et al. (Finance Stoch. 8:311–341, 2004), who find that the arbitrage-free price of a contingent claim coincides with the Black–Scholes price. However, in Çetin et al. (Finance Stoch. 8:311–341, 2004) a larger class of admissible portfolio processes is used, and the replication is achieved in the L ² approximating sense.     

Volume,liquidity, and liquidity risk

Many classes of microstructure models, as well as intuition, suggest that it should be easier to trade when markets are more active. In the data, however, volume and liquidity seem unrelated over time. This paper offers an explanation for this fact based on a simple frictionless model in which liquidity reflects the average risk-bearing capacity of the economy and volume reflects the changing contribution of individuals to that average. Volume and liquidity are unrelated in the model, but volume is positively related to the variance of liquidity, or liquidity risk. Empirical evidence from the U.S. government bond and stock markets supports this new prediction.     

保险市场逆向选择与顺向选择共存研究

保险市场存在着逆向选择。经典逆向选择模型认为,风险高的人会购买更多的保险,但大多数实证研究表明保险市场还存在顺向选择。本文认为,逆向选择和顺向选择虽然对立,但共存于保险市场,在此基础上构建保险市场均衡模型,并进行了仿真研究。     

流动性过剩与农信社流动性不足

2007年以来,为缓解流动性过剩,控制货币信贷过快增长,央行频繁运用公开市场操作和上调存款准备金率等手段,加大货币回收力度.这虽然抑制了银行体系的流动性过剩,但对于作为弱势金融群体的农村信用社来说,紧缩货币政策实施所产生的累积效应对一些经济欠发达山区农信社的流动性管理带来了不利的影响,隐含的支付性风险不容忽视.     

Decimalization,adverse selection,and market maker rents

I address the issue of how decimalization impacts the information acquisition decision of traders. I show that traders have less of an incentive to improve the quality of their information and, consequently, trades tend to be less informative following a reduction in the minimum tick. This result is consistent with the empirical finding that reductions in the minimum tick lead to declines in the adverse selection component, a finding counter to the theoretical predictions in the literature. This result also explains how the predicted savings from decimalization can exceed even total market maker profits. In addition, I show that even if market makers are perfectly competitive, a minimum tick can lead to multiple spread equilibria, some of which being more than one tick away from the underlying, or “no-tick”, equilibrium spread. Finally, I discuss the implications of the model for payment for order flow/internalization and the existence of an optimal tick size.     

Reputation and adverse selection: theory and evidence from eBay

How can a marketplace introduce mechanisms to overcome inefficiencies caused by adverse selection? In this article, I use a unique data set that follows eBay sellers to show that reputation is a major determinant of price variations. I develop a model of sellers' dynamic behavior where sellers have heterogeneous qualities unobservable by buyers. Using reputation as a signal of quality, I structurally estimate the model to uncover buyers' utility and sellers' costs and underlying qualities. I show that removing the reputation mechanism increases low‐quality sellers' market share, lowers prices, and consequently reduces sellers' profit by 66% and consumer surplus by 35%.     

Hedging and liquidity

This article develops a model for evaluating alternative hedgingstrategies for financially constrained firms. A key advantageof the model is the ability to capture the intertemporal effectsof hedging on the firm's financial situation. We characterizethe optimal hedge. A wide range of alternative hedging strategiescan be specified and the model allows us to determine in eachcase if the hedging strategy raises or lowers firms value andby how much. We show that hedging firm value, hedging cash flowfrom operations and hedging sales revenue are not optimal. Thearticle highlights the fact that every hedging strategy comespackaged with a borrowing strategy which requires careful consideration.     

Government intervention and adverse selection costs in foreign exchange markets

An important group of traders in the foreign exchange marketis governments who often adhere to a foreign exchange rate policyof occasional interventions with otherwise floating rates. Inthis article we provide a theoretical model and empirical evidencethat government foreign exchange interventions create significantadverse selection problems for dealers. In particular, our modelshows that the adverse selection component of the foreign exchangespread is positively related to the variance of unexpected interventionand that expected intervention has no impact on the spread.After controlling for inventory and order processing costs,we find that bid-ask spreads increase with U.S. dollar and Germandeutsche mark foreign exchange rate intervention during theperiod 1976-1994. Furthermore, when the intervention is decomposedinto expected and unexpected components, we find a statisticallyand economically significant increase in spreads with the varianceof unexpected intervention, while expected intervention hasno significant impact on spreads.