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...

An equivalent !-martingale measure (E!MM) for a given stochastic process Sis a probability measure R equivalent to the original measure P such that S isan R-!-martingale. Existence of an E!MM is equivalent to a classical absenceof-arbitrage property of S, and is invariant if we replace the...

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...

Motivated by the Chinese experience, we analyze a semi-open economy where the centralbank has access to international capital markets, but the private sector has not. Thisenables the central bank to choose an interest rate different from the international rate.We examine the optimal policy of...

Following a trend of sustained and accelerated growth, the VIXfutures and options market has become a closely followed, active andliquid market. The standard stochastic volatility models | whichfocus on the modeling of instantaneous variance | are unable to t theentire term structure of VIX...

We consider nancial positions belonging to the Banach lattice of bounded measurable functionson a given measurable space. We discuss risk measures generated by general acceptance sets allowingfor capital injections to be invested in a pre-specied eligible asset with an everywhere positive...

For utility maximization problems under proportional transaction costs, it hasbeen observed that the original market with transaction costs can sometimes be replacedby a frictionless shadow market that yields the same optimal strategy and utility. However,the question of whether or not this...

There is strong empirical evidence that the pricing kernel is Ushaped,which provides a way to explain the substantial coskewnesspremium. Existing studies typically use a polynomial approximationof the pricing kernel. Problematically, these polynomials have, inmost cases, increasing parts by...