In this thesis we deal with different topics in financial mathematics, that are all related to market imperfections and to the fundamental technique of utility maximization. The work consists of three parts. In the first one, which is based on two papers, we consider the problem of optimal...

We study asset prices in an economy where some investors classify risky assets into different styles and move funds back and forth between these styles depending on their relative performance. Our assumptions imply that news about one style can affect the prices of other apparently unrelated...

Can banks maintain their advantage as liquidity providers when they are heavily exposed to a financial crisis? The standard argument - that banks can - hinges on deposit inflows that are seeking a safe haven and provide banks with a natural hedge to fund drawn credit lines and other commitments....

We review a recent approach to understanding the equity premium puzzle. The key elements of this approach are loss aversion and narrow framing, two well-known features of decision-making under risk in experimental settings. In equilibrium, models that incorporate these ideas can generate a large...

We study the asset pricing implications of Tversky and Kahneman's (1992) cumulative prospect theory, with particular focus on its probability weighting component. Our main result, derived from a novel equilibrium with non-unique global optima, is that, in contrast to the prediction of a standard...

A number of studies have identifed patterns of positive correlation of returns, or comovement, among different traded securities. We distinguish three views of such comovement. The traditional 'fundamentals' view explains the comovement of securities through positive correlations in the rational...

This Paper studies equilibrium asset pricing with liquidity risk (the risk arising from unpredictable changes in liquidity over time). It is shown that the required return on a security depends on its expected illiquidity, the covariances of its own return, illiquidity with market return, and...

Behavioral finance argues that some financial phenomena can plausibly be understood using models in which some agents are not fully rational. The field has two building blocks: limits to arbitrage, which argues that it can be difficult for rational traders to undo the dislocations caused by less...

We use portfolio theory to quantify the efficiency of state-level sectoral patterns of production in the United States. On the basis of observed growth in sectoral value added output, we calculate for each state the efficient frontier for investments in the real economy, the efficient Sharpe...

One of the most striking portfolio puzzles is the %u201Cdisposition effect%u201D: the tendency of individuals to sell stocks in their portfolios that have risen in value since purchase, rather than fallen in value. Perhaps the most prominent explanation for this puzzle is based on prospect...