The Valuation of Contingent Claims under Portfolio Constraints: Reservation Buying and Selling Prices

With constrained portfolios contingent claims do not generally havea unique price that rules out arbitrage opportunities.Earlier studies have demonstratedthat when there are constraints on the hedge portfolio,a no-arbitrage price interval for any contingent claim exists.I consider the more realistic case where the constraints are imposed on the total portfolio of each investor and define reservation buying and selling prices for contingent claims. I derive propertiesof these prices, show how they can be computed numerically, and study two simple examples in which the reservation prices and the corresponding hedging strategies are compared to the Black–Scholes setting.     

Model-free hedge ratios and scale-invariant models

A price process is scale-invariant if and only if the returns distribution is independent of the price measurement scale. We show that most stochastic processes used for pricing options on financial assets have this property and that many models not previously recognised as scale-invariant are indeed so. We also prove that price hedge ratios for a wide class of contingent claims under a wide class of pricing models are model-free. In particular, previous results on model-free price hedge ratios of vanilla options based on scale-invariant models are extended to any contingent claim with homogeneous pay-off, including complex, path-dependent options. However, model-free hedge ratios only have the minimum variance property in scale-invariant stochastic volatility models when price–volatility correlation is zero. In other stochastic volatility models and in scale-invariant local volatility models, model-free hedge ratios are not minimum variance ratios and our empirical results demonstrate that they are less efficient than minimum variance hedge ratios.     

Modelling the Currency Forward Risk Premium: A New Perspective

In this paper we seek to develop a new approach to the time series analysis of foreign exchange risk premia. We do so by assuming a geometric Brownian process for the spot exchange rate and expressing the no-arbitrage spot-forward price relationship under the historical probability measure. We are thereby able to obtain a stochastic differential equation system linking the spot exchange rate, the forward exchange rate and the risk premium (modelled directly as a mean-reverting diffusion process) which we estimate using Kalman filtering techniques. We are able to use observations at a range of frequencies since the framework we set up does not involve overlapping observations. The model is then applied to the French Franc/USD, DEM/USD, GBP/USD, and Japanese Yen/USD exchange rates from 1 January 1990 to 31 December 1998. For all currencies we find evidence that the forward risk premium is stationary and exhibits substantial positive time variation.     

The Forward Premium in the Nord Pool Power Market

This article investigates the forward premium of futures contracts in the Nordic power market for the time period from January 2004 to December 2013. We find that futures prices are biased predictors of the subsequent spot prices and that there is a significant forward premium in the Nord Pool market, particularly during the winter and autumn. We analyze the impact from several factors on the forward premium. The spot price, and the deviation of water inflow from its usual level, positively affect the forward premium. The variance of the spot price also has a positive effect on the forward premium, but only for the contract closest to delivery.     

Optimal hedging in an extended binomial market under transaction costs

We develop an approach to optimal hedging of a contingent claim under proportional transaction costs in a discrete time financial market model which extends the binomial market model with transaction costs. Our model relaxes the binomial assumption on the stock price ratios to the case where the stock price ratio distribution has bounded support. Non-self-financing hedging strategies are studied to construct an optimal hedge for an investor who takes a short position in a European contingent claim settled by delivery. We develop the theoretical basis for our optimal hedging approach, extending results obtained in our previous work. Specifically, we derive a no-arbitrage option price interval and establish properties of the non-self-financing strategies and their residuals. Based on the theoretical foundation, we develop a computational algorithm for optimizing an investor relevant criterion over the set of admissible non-self-financing hedging strategies. We demonstrate the applicability of our approach using both simulated data and real market data.     

Pricing a contingent claim liability with transaction costs using asymptotic analysis for optimal investment

We price a contingent claim liability (claim for short) using a utility indifference argument. We consider an agent with exponential utility, who invests in a stock and a money market account with the goal of maximizing the utility of his investment at the final time T in the presence of a proportional transaction cost ε>0 in two cases: with and without a claim. Using the heuristic computations of Whalley and Wilmott (Math. Finance 7:307–324, 1997), under suitable technical conditions, we provide a rigorous derivation of the asymptotic expansion of the value function in powers of \(\varepsilon^{\frac{1}{3}}\) in both cases with and without a claim. Additionally, using the utility indifference method, we derive the price of the claim at the leading order of \(\varepsilon^{\frac{2}{3}}\) . In both cases, we also obtain a “nearly optimal” strategy, whose expected utility asymptotically matches the leading terms of the value function. We also present an example of how this methodology can be used to price more exotic barrier-type contingent claims.     

A new approach for option pricing under stochastic volatility

We develop a new approach for pricing European-style contingent claims written on the time T spot price of an underlying asset whose volatility is stochastic. Like most of the stochastic volatility literature, we assume continuous dynamics for the price of the underlying asset. In contrast to most of the stochastic volatility literature, we do not directly model the dynamics of the instantaneous volatility. Instead, taking advantage of the recent rise of the variance swap market, we directly assume continuous dynamics for the time T variance swap rate. The initial value of this variance swap rate can either be directly observed, or inferred from option prices. We make no assumption concerning the real world drift of this process. We assume that the ratio of the volatility of the variance swap rate to the instantaneous volatility of the underlying asset just depends on the variance swap rate and on the variance swap maturity. Since this ratio is assumed to be independent of calendar time, we term this key assumption the stationary volatility ratio hypothesis (SVRH). The instantaneous volatility of the futures follows an unspecified stochastic process, so both the underlying futures price and the variance swap rate have unspecified stochastic volatility. Despite this, we show that the payoff to a path-independent contingent claim can be perfectly replicated by dynamic trading in futures contracts and variance swaps of the same maturity. As a result, the contingent claim is uniquely valued relative to its underlying’s futures price and the assumed observable variance swap rate. In contrast to standard models of stochastic volatility, our approach does not require specifying the market price of volatility risk or observing the initial level of instantaneous volatility. As a consequence of our SVRH, the partial differential equation (PDE) governing the arbitrage-free value of the contingent claim just depends on two state variables rather than the usual three. We then focus on the consistency of our SVRH with the standard assumption that the risk-neutral process for the instantaneous variance is a diffusion whose coefficients are independent of the variance swap maturity. We show that the combination of this maturity independent diffusion hypothesis (MIDH) and our SVRH implies a very special form of the risk-neutral diffusion process for the instantaneous variance. Fortunately, this process is tractable, well-behaved, and enjoys empirical support. Finally, we show that our model can also be used to robustly price and hedge volatility derivatives.     

Central Bank Policy Paths and Market Forward Rates: A Simple Model

Increasingly many central banks announce likely paths for future policy rates. Recent experience suggests that market forward rates can differ substantially from those announced. Models commonly adopted in policy analysis ignore such differences. This paper studies a simple model that can capture deviations between announced paths and market forward rates. We detail the macroeconomic transmission of such deviations and show how the model can inform policy deliberations.     

Hedging Multiperiod Forward Commitments: The Case of Period-by-Period Quantity Uncertainty

This article considers the hedging problem of a producer with along-term forward commitment to deliver a commodity at multiple futurepoints in time. The aggregate quantity to be delivered over time is knownwith certainty; however, the period-by-period quantity is determined bythe customer and is unknown to the producer. A minimum-variancemultiperiod futures position that considers both price uncertainty andperiod-by-period quantity uncertainty is derived. The following resultsare obtained: The individual effects of price uncertainty and quantityuncertainty on the multiperiod minimum-variance are separable. In thetwo-period case, if the spot price is expected to decrease over time, therisk-minimizing hedge considering both price and quantity uncertaintiesis greater than that which considers price uncertainty only. If the spotprice is expected to increase over time, then the hedger would beover-hedged if only price uncertainty were considered. Convenience yieldpromotes a larger risk-minimizing futures position, whereas storage costsand financial costs reduce the size of the risk-minimizing futuresposition. In the multiperiod case, if forward prices are unbiasedestimators of future spot prices, or if spot prices are expected todecrease over time, then quantity uncertainty increases the size of therisk-minimizing hedge. If spot prices are expected to increase, then theeffect of period-by-period quantity uncertainty isindeterminate.     

Asset pricing theory for two price economies

We show that nonlinearly discounted nonlinear martingales are related to no arbitrage in two price economies as linearly discounted martingales were related to no arbitrage in economies satisfying the law of one price. Furthermore, assuming risk acceptability requires a positive physical expectation, we demonstrate that expected rates of return on ask prices should be dominated by expected rates of return on bid prices. A preliminary investigation conducted here, supports this hypothesis. In general we observe that asset pricing theory in two price economies leads to asset pricing inequalities. A model incorporating both nonlinear discounting and nonlinear martingales is developed for the valuation of contingent claims in two price economies. Examples illustrate the interactions present between the severity of measure changes and their associated discount rates. As a consequence arbitrage free two price economies can involve unique discount curves and measure changes that are however specific to both the product being priced and the trade direction. Furthermore the developed valuation operators call into question the current practice of Debt Valuation Adjustments.     

Multiperiod Strip Hedging of Forward Commitments

This paper empirically compares two multiperiod hedging strategies—a strip hedge and a stack-and-roll hedge—to hedge a forward commitment. The multiperiod strip hedge is found to outperform the stack-and-roll hedge when forward prices are subject to multiple sources of price uncertainty and to perform no better when only one source of uncertainty is present. Moreover, the relative superiority of the strip hedge increases with the presence of multiple sources of uncertainty. Last, the strip hedge is found to be more costly to trade than the stack-and-roll hedge; however, its cost varies directly with its superiority at reducing risk.     

Pricing catastrophe options with stochastic claim arrival intensity in claim time

We model claim arrival and loss uncertainties jointly in a doubly-binomial framework to price an Asian-style catastrophe (CAT) option with a non-traded underlying loss index using the no-arbitrage martingale pricing methodology. We span these uncertainties by benchmarking to the shadow price of a one-claim bond and the premium of a reinsurance contract. We implement a stochastic time change from calendar time to claim time to more efficiently price the CAT option as a random sum – a binomial sum of claim time binomial Asian option prices. This choice of the operational time dimension allows us to incorporate different patterns of catastrophe arrivals by adjusting the claim arrival probability. We demonstrate this versatility by incorporating a mean-reverting Ornstein-Uhlenbeck intensity arrival process. Simulation results verify our model predictions and demonstrate how the claim arrival probability varies with the expected claim arrival intensity.     

Housing Quality in the Forward Contracts Market

Developers often conduct forward sales (or presales) before building completion to relieve financial risk and burden. However, there are worries that housing units sold in this way will turn out to be substandard because developers, who have been paid for the unfinished units, may have incentives to cut costs by lowering the quality. This is a typical moral hazard problem. Nonetheless, forward sales have been very popular in some Asian cities such as Hong Kong, Singapore, and Taiwan. A plausible explanation is that the market has efficiently adjusted the forward price for this potential quality problem according to developers’ reputations. This paper aims to theoretically explain and empirically test (1) whether reputation is reflected in forward prices and (2) whether the expected quality level matches with the actual quality level. Using the forward and spot sales data of the Hong Kong real estate market, we found that even though housing quality was not observable during presales, the market was able to capitalize developers’ reputations into forward prices accurately. This suggests that the optimal strategy for developers is to stick to the quality level implied by their reputations. A paper submitted to Journal of Real Estate Finance and Economics. A Special Issue for the 2005 NUS-HKU Symposium on Real Estate Research.     

CoCo Bonds,Conversion Prices and Risk Shifting Incentives. How Does the Conversion Ratio Affect Management's Behaviour?

The aim of this paper is to analyze risk shifting incentives for managers and shareholders of the financial institution issuing a CoCo bond. We assess the role of the conversion price settlement in enhancing both shareholders’ and management's discipline. Three recent contingent reverse convertible deals are analyzed, with the intention of showing how shareholder conversion returns are linked to the conversion ratio. The findings demonstrate that, in the case of an ingoing or ongoing crisis, a poor settlement of the conversion ratio could exacerbate both debt overhang and risk shifting issues. This will end in discouraging bank management from issuing new equity and from investing in low risk assets. We argue that a contingent bond triggered on Basel III capital requirement ratios and having a significantly discounted conversion price reduces risk shifting incentives. Moreover, we illustrate how the unexpected wealth transfers between CoCo bondholders and shareholders tends to zero when the bond face value is higher than the current stock market price and there is a concentration of bond subscribers. Accordingly, regulators should consider and oversee not only the conversion trigger but also all the other features of a contingent capital security, especially the conversion ratio.     

Coherent hedging in incomplete markets

In incomplete financial markets, not every contingent claim can be perfectly replicated by a self-financing strategy. In this paper, we minimize the risk that the value of the hedging portfolio falls below the payoff of the claim at time T. We use a coherent risk measure, introduced by Artzner et al., to measure the risk of the shortfall. The dynamic optimization problem of finding a self-financing strategy that minimizes the coherent risk of the shortfall can be split into a static optimization problem and a representation problem. We will deduce necessary and sufficient optimality conditions for the static problem using convex duality methods. The solution of the static optimization problem turns out to be a randomized test with a typical 0–1 structure. Our results improve those obtained by Nakano. The optimal hedging strategy consists of superhedging a modified claim that is the product of the original payoff and the solution to the static problem.     

Estimating the Strategic Value of Long-Term Forward Purchase Contracts Using Auction Models

We demonstrate how an auction model can be used in a traditional capital budgeting context to assign a value to the strategic advantage of long-term forward contracts. Research in the field of industrial organization has pointed to the danger of ex post opportunistic bargaining as a motivation for the use of forward contracts in natural resources and manufactured products, but no operational procedure exists for estimating the value secured by these contracts. Arbitrage methods for valuing forward contracts assume a competitive market in which the factors creating the bargaining problem and motivating the use of long-term contracts are not present. Use of the model is illustrated in the case of take-or-pay contracts for natural gas.