We solve the problem of mean-variance hedging for general semimartingale models via stochastic control methods. After proving that the value process of the associated stochastic control problem has a quadratic structure, we characterise its three coefficient processes as solutions of...

We propose a simplified approach to mean-variance portfolio problems by changingtheir parametrisation from trading strategies to final positions. This allows us to treat,under a very mild no-arbitrage-type assumption, a whole range of quadratic optimisationproblems by simple mathematical tools...

The Markowitz problem consists of finding in a financial market a self-financingtrading strategy whose final wealth has maximal mean and minimal variance. Westudy this in continuous time in a general semimartingale model and under coneconstraints: Trading strategies must take values in a...

We study mean-variance hedging under portfolio constraints in a general semi-martingale model. The constraints are formulated via predictable correspondences,meaning that the trading strategy is restricted to lie in a closed convex set whichmay depend on the state and time in a predictable way....

The purpose of this paper is two-fold. First is to extend the notions of an n-dimensional semimartingaleand its stochastic integral to a piecewise semimartingale of stochastic dimension. The propertiesof the former carry over largely intact to the latter, avoiding some of the pitfalls of...

We develop an econometric methodology to infer the path of risk premia from large unbalancedpanel of individual stock returns. We estimate the time-varying risk premia implied by conditional linearasset pricing models where the conditioning includes instruments common to all assets and asset...

We explore the pricing of variance risk by decomposing stocks' total variance into systematicand idiosyncratic return variances. While systematic variance risk exhibits a negative priceof risk, common shocks to the variances of idiosyncratic returns carry a large positive riskpremium. This...

We analyze numerically the superreplication problem and the associatedhedging strategy in an illiquid binomial market. We prove theexistence of an optimal feedback strategy for European and barrier optionsand compute it numerically by means of a dynamic programmingprinciple. We exhibit that the...

Many postulated relations in finance imply that expected asset returns should monotonicallyincrease in a certain characteristic. To examine the validity of such a claim, onetypically considers a finite number of return categories, ordered according to the underlyingcharacteristic. A standard...

There has been a long debate about whether speculators are stabilizing or not.We consider a model where speculators have a stabilizing role in normal times,but may also provoke large risk panics. The very feature that makes arbitrageursliquidity providers in normal times, namely their tolerance...