90 research outputs found
A note on market completeness with American put options
We consider a non necessarily complete financial market with one bond and one risky asset, whose price process is modelled by a suitably integrable, strictly positive, cà dlà g process over . Every option price is defined as the conditional expectation under a given equivalent (true) martingale measure , the same for all options. We show that every positive contingent claim on can be approximately replicated (in -sense) by investing dynamically in the underlying and statically in all American put options (of every strike price and with the same maturity ). We also provide a counter-example to static hedging with European call options of all strike prices and all maturities .
Multivariate utility maximization with proportional transaction costs and random endowment
In this paper we deal with a utility maximization problem at finite horizon on a continuous-time market with conical (and time varying) constraints (particularly suited to model a currency market with proportional transaction costs). In particular, we extend the results in Campi and Owen (2011) to the situation where the agent is initially endowed with a random and possibly unbounded quantity of assets. We start by studying some basic properties of the value function (which is now defined on a space of random variables), then we dualize the problem following some convex analysis techniques which have proven very useful in this field of research. We finally prove the existence of a solution to the dual and (under an additional boundedness assumption on the endowment) to the primal problem. The last section of the paper is devoted to an application of our results to utility indifference pricing.Transaction costs ; Foreign exchange market ; Multivariate utility function ; Optimal portfolio ; Duality theory ; Random endowment ; Utility-based pricing
Multivariate Utility Maximization with Proportional Transaction Costs.
We present an optimal investment theorem for a currency exchange model with random and possibly discontinuous proportional transaction costs. The investor’s preferences are represented by a multivariate utility function, allowing for simultaneous consumption of any prescribed selection of the currencies at a given terminal date. We prove the existence of an optimal portfolio process under the assumption of asymptotic satiability of the value function. Sufficient conditions for asymptotic satiability of the value function include reasonable asymptotic elasticity of the utility function, or a growth condition on its dual function. We show that the portfolio optimization problem can be reformulated in terms of maximization of a terminal liquidation utility function, and that both problems have a common optimizer.Duality Theory; Lagrange Duality; Multivariate Utility Function; Asymptotic Satiability; Optimal Portfolio; Transaction Costs; Foreign Exchange Market;
On the spot-futures no-arbitrage relations in commodity markets
In commodity markets the convergence of futures towards spot prices, at the
expiration of the contract, is usually justified by no-arbitrage arguments. In
this article, we propose an alternative approach that relies on the expected
profit maximization problem of an agent, producing and storing a commodity
while trading in the associated futures contracts. In this framework, the
relation between the spot and the futures prices holds through the
well-posedness of the maximization problem. We show that the futures price can
still be seen as the risk-neutral expectation of the spot price at maturity and
we propose an explicit formula for the forward volatility. Moreover, we provide
an heuristic analysis of the optimal solution for the
production/storage/trading problem, in a Markovian setting. This approach is
particularly interesting in the case of energy commodities, like electricity:
this framework indeed remains suitable for commodities characterized by
storability constraints, when standard no-arbitrage arguments cannot be safely
applied
Change of numeraire in the two-marginals martingale transport problem
In this paper we apply change of numeraire techniques to the optimal
transport approach for computing model-free prices of derivatives in a two
periods model. In particular, we consider the optimal transport plan
constructed in \cite{HobsonKlimmek2013} as well as the one introduced in
\cite{BeiglJuil} and further studied in \cite{BrenierMartingale}. We show that,
in the case of positive martingales, a suitable change of numeraire applied to
\cite{HobsonKlimmek2013} exchanges forward start straddles of type I and type
II, so that the optimal transport plan in the subhedging problems is the same
for both types of options. Moreover, for \cite{BrenierMartingale}'s
construction, the right monotone transference plan can be viewed as a mirror
coupling of its left counterpart under the change of numeraire. An application
to stochastic volatility models is also provided
Assessing Credit with Equity: A CEV Model with Jump to Default
Unlike in structural and reduced-form models, we use equity as a liquid and observable primitive to analytically value corporate bonds and credit default swaps. Restrictive assumptions on the firmâs capital structure are avoided. Default is parsimoniously represented by equity value hitting the zero barrier. Default can be either predictable, according to a CEV process that yields a positive probability of diffusive default and enables the leverage effect, or unpredictable, according to a Poisson-process jump that implies non-zero credit spreads for short maturities. Easy cross-asset hedging is enabled. By means of a carefully specified pricing kernel, we also enable analytical credit-risk management under possibly systematic jump-to-default risk.Equity, Corporate Bonds, Credit Default Swaps, Constant-Elasticity-of-Variance (CEV) Diffusion, Jump to Default
Mean field games with controlled jump-diffusion dynamics: Existence results and an illiquid interbank market model
We study a family of mean field games with a state variable evolving as a
multivariate jump diffusion process. The jump component is driven by a Poisson
process with a time-dependent intensity function. All coefficients, i.e. drift,
volatility and jump size, are controlled. Under fairly general conditions, we
establish existence of a solution in a relaxed version of the mean field game
and give conditions under which the optimal strategies are in fact Markovian,
hence extending to a jump-diffusion setting previous results established in
[30]. The proofs rely upon the notions of relaxed controls and martingale
problems. Finally, to complement the abstract existence results, we study a
simple illiquid inter-bank market model, where the banks can change their
reserves only at the jump times of some exogenous Poisson processes with a
common constant intensity, and provide some numerical results.Comment: 37 pages, 6 figure
A probabilistic numerical method for optimal multiple switching problem and application to investments in electricity generation
In this paper, we present a probabilistic numerical algorithm combining
dynamic programming, Monte Carlo simulations and local basis regressions to
solve non-stationary optimal multiple switching problems in infinite horizon.
We provide the rate of convergence of the method in terms of the time step used
to discretize the problem, of the size of the local hypercubes involved in the
regressions, and of the truncating time horizon. To make the method viable for
problems in high dimension and long time horizon, we extend a memory reduction
method to the general Euler scheme, so that, when performing the numerical
resolution, the storage of the Monte Carlo simulation paths is not needed.
Then, we apply this algorithm to a model of optimal investment in power plants.
This model takes into account electricity demand, cointegrated fuel prices,
carbon price and random outages of power plants. It computes the optimal level
of investment in each generation technology, considered as a whole, w.r.t. the
electricity spot price. This electricity price is itself built according to a
new extended structural model. In particular, it is a function of several
factors, among which the installed capacities. The evolution of the optimal
generation mix is illustrated on a realistic numerical problem in dimension
eight, i.e. with two different technologies and six random factors
Utility indifference pricing and hedging for structured contracts in energy markets
In this paper we study the pricing and hedging of structured products in
energy markets, such as swing and virtual gas storage, using the exponential
utility indifference pricing approach in a general incomplete multivariate
market model driven by finitely many stochastic factors. The buyer of such
contracts is allowed to trade in the forward market in order to hedge the risk
of his position. We fully characterize the buyer's utility indifference price
of a given product in terms of continuous viscosity solutions of suitable
nonlinear PDEs. This gives a way to identify reasonable candidates for the
optimal exercise strategy for the structured product as well as for the
corresponding hedging strategy. Moreover, in a model with two correlated
assets, one traded and one nontraded, we obtain a representation of the price
as the value function of an auxiliary simpler optimization problem under a risk
neutral probability, that can be viewed as a perturbation of the minimal
entropy martingale measure. Finally, numerical results are provided.Comment: 32 pages, 5 figure
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