Optimal portfolios under worst-case scenarios

In standard portfolio theories such as Mean–Variance optimization, expected utility theory, rank dependent utility heory, Yaari’s dual theory and cumulative prospect theory, the worst outcomes for optimal strategies occur when the market declines (e.g. during crises), which is at odds with the needs of many investors. Hence, we depart from the traditional settings and study optimal strategies for investors who impose additional constraints on their final wealth in the states corresponding to a stressed financial market. We provide a framework that maintains the stylized features of the SP/A theory while dealing with the goal of security in a more flexible way. Preferences become state-dependent, and we assess the impact of these preferences on trading decisions. We construct optimal strategies explicitly and show how they outperform traditional diversified strategies under worst-case scenarios.     

Optimal design of equity-linked products with a probabilistic constraint

There is a rich variety of tailored investment products available to the retail investor. These products combine upside participation in bull markets with downside protection in bear markets. Examples include the equity-linked products sold by insurance companies and the structured products marketed by banks. This paper examines a particular contract design for products of this nature. The paper finds the optimal design from the investor's viewpoint. It is assumed that the investor wishes to maximize expected utility of the terminal wealth subject to certain constraints. These constraints include a guaranteed rate of return as well as the opportunity to outperform a benchmark portfolio with a given probability. We derive the explicit form of the optimal design assuming both constraints apply and we illustrate the nature of the solution using some specific examples.     

Hedging Housing Risk in London

This paper investigates the benefits of allowing households to compensate the portfolio distortion due to their housing consumption through investments in housing price derivatives. Focusing on the London market, we show that a major loss from over-investment in housing is that households are forced to hold a very risky portfolio. However, the strong performance of the London housing market means that little is lost in terms of expected returns. Even households with limited wealth are better off owning their home rather than renting and investing in financial assets, as long as they are willing to face the financial risk involved. In this context, access to housing price derivatives would benefit most poor homeowners looking to limit their risk exposure. It would also benefit wealthier investors looking for the high returns provided by housing investments without the costs of direct ownership of properties. Comparisons with French, Swedish and U.S. data provide a broader perspective on our findings.     

Hedging Housing Risk*

An unusually rich source of data on housing prices in Stockholm is used to analyze the investment implications of housing choices. This empirical analysis derives market-wide price and return series for housing investment during a 13-year period, and it also provides estimates of the individual-specific, idiosyncratic, variation in housing returns. Because the idiosyncratic component follows an autocorrelated process, the analysis of portfolio choice is dependent upon the holding period. We analyze the composition of household investment portfolios containing housing, common stocks, stocks in real estate holding companies, bonds, and t-bills. For short holding periods, the efficient portfolio contains essentially no housing. For longer periods, low-risk portfolios contain 15 to 50 percent housing. These results suggest that there are large potential gains from policies or institutions that would permit households to hedge their lumpy investments in housing. We estimate the potential value of hedges in reducing risk to households, yet yielding the same investment returns. The value is surprisingly large, especially to poorer homeowners.     

Stochastic Interest Rates and the Bond-Stock Mix

The optimal bond-stock mix is examined in light of an apparentinconsistency between the Tobin Separation Theorem and the adviceof popular investment advisors which has been pointed out byCanner et al. (1997).It is shown that the apparent inconsistencyis largely explicable in terms of the hedging demands of optimisinglong-term investors in an environment in which the investmentopportunity set is subject to stochastic shocks. The analysispoints to the importance of considering investors' time horizonsin analyzing optimal portfolio policies.     

Stochastic Interest Rates and the Bond-Stock Mix

The optimal bond-stock mix is examined in light of an apparent inconsistency between the Tobin Separation Theorem and the advice of popular investment advisors which has beenpointed out by Canner et al. (1997). It is shown that the apparent inconsistency is largely explicable in terms of the hedging demands of optimising long-term investors in an environment in which the investment opportunity set is subject to stochastic shocks. The analysis points to the importance of considering investors' time horizons in analyzing optimal portfolio policies.     

Stock Market Mean Reversion and the Optimal Equity Allocation of a Long-Lived Investor

This paper solves numerically the intertemporalconsumption and portfolio choiceproblem of an infinitely-lived investor whofaces a time-varying equity premium.The solutions we obtain are very similarto the approximate analytical solutionsof Campbell and Viceira (1999), except atthe upper extreme of the state spacewhere both the numerical consumption andportfolio rules flatten out.We also consider a constrained version ofthe problem in which the investor facesborrowing and short-sales restrictions.These constraints bind when the equitypremium moves away from its mean in eitherdirection, and are particularly severe forrisk-tolerant investors. The constraints havesubstantial effects on optimalconsumption, but much more modest effects onoptimal portfolio choice in theregion of the state space where they are notbinding.     

Utility maximizing portfolio insurance strategies when hedgers consider the impact of their trading on security prices

Portfolio insurance strategies can destabilize markets to such an extent that they may be counterproductive. Destabilization results when hedgers take share prices as given and follow exogenously specified price-based trading rules. We recognize that such trading rules may not be utility maximizing and that hedging affects share prices. Accordingly, we develop a portfolio insurance strategy where hedgers consider the impact of their trading on prices and endogenize their trading rule which is obtained by maximizing expected utility. Moreover, our strategy does not require the dissemination of information about the extent of portfolio-insurance based hedging activity in the economy.     

Optimal Bond Portfolio for Investors with Long Time Horizons

We study the optimal bond portfolio for an investor with long time horizonusing Japanese interest rate data. A simple one-factor term structure modelis used for our numerical example. The optimal portfolio is computed using thetechnique of stochastic flows and Monte Carlo simulation. The hedgingportfolio is not negligible and the mean variance portfolio is very sensitiveto parameter values. The optimal portfolio is highly leveraged for a typicalparameter value. The investor holds a zero-coupon bond because of the lowerbound restriction on investor's wealth. The lower bound constraint may makethe optimal portfolio more realistic.     

The Optimal Construction of Internationally Diversified Equity Portfolios Hedged Against Exchange Rate Uncertainty

Much of the empirical work on hedging exchange rate exposure in portfolios of financial assets has used a unitary hedge ratio, or a currency overlay. Alternatively, the currencies themselves can be treated as assets and the position in them optimized. This study empirically tests whether the ex post results of recent studies, which conclude that currencies should themselves be optimized, stand up under parameter uncertainty. It may very well be that ex ante, when parameter inputs must be estimated from historical data, the attempt to determine the optimal currency weights results in inferior performance in comparison to using a simple unitary hedging strategy, or even unhedged international investment. The results suggest that a local currency return unitary hedging strategy works best in the presence of parameter uncertainty.     

两类银行组合型汇率避险产品应引起关注

随着企业对汇率风险关注度的提高,企业对汇率避险产品的需求日趋旺盛。文章以江苏省为例,重点考察了两类组合型汇率避险产品的运作模式及其对外汇管理和跨境资金流动的相关影响,并从加强对外债和银行综合头寸管理、鼓励银行合理创新产品和构建完善的汇率避险产品统计监测体系等方面,就规范汇率避险产品发展提出建议。