The sphere of modern financial economics encompases finance, micro investment theory and much of the economics of uncertainty. As is evident from its influence on other branches of economics including public finance, industrial organization and monetary theory, the boundaries of this sphere are both permeable and flexible. The complex interactions of time and uncertainty guarantee intellectual challenge and intrinsic excitement to the study of financial economics. Indeed, the mathematics of the subject contain some of the most interesting applications of probability and optimization theory. But for all its mathematical refinement, the research has nevertheless had a direct and significant influence on practice. It was not always thus. Thirty years ago, finance theory was little more than a collection of anecdotes, rules of thumb, and manipulations of accounting data with an almost exclusive focus on corporate financial management. There is no need in this meeting of the guild to recount the subsequent evolution from this conceptual potpourri to a rigorous economic

ABSTRACT Duality theory is employed to provide necessary and sufficient conditions for portfolios on the minimum‐variance frontier to have positive investment proportions in all assets. These conditions involve the feasibility of portfolios that have non‐negative correlation with all assets and positive correlation with at least one. Using these results, several “qualitative” results concerning the signs of investment proportions in efficient portfolios are proved. It is argued that the conditions that ensure all‐positive weights in efficient portfolios are intuitively compelling and are not unique to the CAPM. With large numbers of assets, however, the signs of weights in minimum‐variance portfolios can be very sensitive to slight departures from these conditions due to, for example, sampling error.

ABSTRACT This paper theoretically evaluates the robustness of the Security Market Line relationship when the market proxy employed is not mean‐variance efficient. The analysis focuses on the behavior of the “benchmark errors,” the deviations of assets and portfolios from the Security Market Line. First, we characterize how the location of an asset in mean‐variance space determines its benchmark error. Then the continuity properties of the benchmark errors are studied. The results indicate that the magnitudes of the errors exhibit continuous but not uniformly continuous behaviors. The relative rankings based on deviations from the Security Market Line, however, exhibit some severe discontinuities. In fact, these can be exactly reversed for two proxies arbitrarily close in mean‐variance space.

Duality theory is employed to provide necessary and sufficient conditions for portfolios on the minimum-variance frontier to have positive investment proportions in all assets. These conditions involve the feasibility of portfolios that have non-negative correlation with all assets and positive correlation with at least one. Using these results, several “qualitative” results concerning the signs of investment proportions in efficient portfolios are proved. It is argued that the conditions that ensure all-positive weights in efficient portfolios are intuitively compelling and are not unique to the CAPM. With large numbers of assets, however, the signs of weights in minimum-variance portfolios can be very sensitive to slight departures from these conditions due to, for example, sampling error.

ABSTRACT Sell‐off activities arise when a firm sells part of its assets (e.g., a segment, a division, etc.) but continues to exist in essentially the same form. This study investigates the effect of voluntary sell‐offs on stock returns. From a sample of over 1000 sell‐off events (first public announcements), the evidence shows that both sellers and buyers earn significant positive excess returns from these transactions. The excess returns earned by buyers are smaller than those earned by sellers. There is also evidence that sell‐off announcements are preceded by a period of significant negative returns for the sellers which suggests that the sellers, on average, performed poorly prior to their sell‐off activities.

This paper focuses on the conditions under which banks are subject to currency and country risks on their dollar-denominated loans to foreign firms and governments. We conclude that currency risk is a function of the rates of domestic and foreign inflation, deviations from purchasing power parity, and the effect of these deviations on the firm's and the nation's dollar-equivalent cash flows. Country risk is largely determined by the variability of the nation's terms of trade and the government's willingness to allow the national economy to adjust rapidly to changing economic fortunes.