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.

We value a firm that pays its cash flows to equity through share repurchases in a dynamic environment where personal taxes are paid on capital gains upon realization. The cost of capital is reduced by approximately 0.8% through the use of repurchases relative to dividends. We use the empirical distribution of pre-tax free cash flows in Fama and French (1999) to evaluate the tradeoffs between the costs of financial distress, the personal-tax advantages of equity, and the corporate-tax advantage to debt. The optimal capital structure is interior with a 3% bankruptcy cost.

Swedish government lottery bonds have coupon payments determined by lottery. They offer a unique opportunity to study a security with uncertain payoffs having a known, observable distribution. The risk associated with the lotteries is idiosyncratic by construction and should not command a risk premium in equilibrium. The bonds are traded in two forms, allowing us to evaluate the rewards to bearing extra lottery risk. Despite its idiosyncratic nature, we find prices appear to reflect aversion to this risk. We evaluate the empirical determinants of this differential pricing and possible explanations for it.

Swedish government lottery bonds have coupon payments determined by lottery. They offer a unique opportunity to study a security with uncertain payoffs having a known, observable distribution. The risk associated with the lotteries is idiosyncratic by construction and should not command a risk premium in equilibrium. The bonds are traded in two forms, allowing us to evaluate the rewards to bearing extra lottery risk. Despite its idiosyncratic nature, we find prices appear to reflect aversion to this risk. We evaluate the empirical determinants of this differential pricing and possible explanations for it.

[We derive and test a dynamic discrete-time model of asset returns. Both the risks of individual securities and equilibrium risk premia change predictably in the model, but these changes can be attributed to movements in the returns and prices of only two well-diversified portfolios. Any other components of returns should be unpredictable. Using the generalized method of moments, the model is estimated and tested on portfolios of equities. We find the data supportive of the model's restrictions, even when instruments designed to capture the January effect are employed.]

We characterize the conditions under which efficient portfolios put small weights on individual assets. These conditions bound mean returns with measures of average absolute covariability between assets. The bounds clarify the relationship between linear asset pricing models and well-diversified efficient portfolios. We argue that the extreme weightings in sample efficient portfolios are due to the dominance of a single factor in equity returns. This makes it easy to diversify on subsets to reduce residual risk, while weighting the subsets to reduce factor risk simultaneously. The latter involves taking extreme positions. This behavior seems unlikely to be attributable to sampling error.

The authors characterize the conditions under which efficient portfolios put small weights on individual assets. These conditions bound mean returns with measures of average absolute covariability between assets. The bounds clarify the relationship between linear asset pricing models and well-diversified efficient portfolios. The authors argue that the extreme weightings in sample efficient portfolios are due to the dominance of a single factor in equity returns. This makes it easy to diversify on subsets to reduce residual risk, while weighing the subsets to reduce factor risk simultaneously. The latter involves taking extreme positions. This behavior seems unlikely to be attributable to sampling error.

We characterize the conditions under which efficient portfolios put small weights on individual assets. These conditions bound mean returns with measures of average absolute covariability between assets. The bounds clarify the relationship between linear asset pricing models and well‐diversified efficient portfolios. We argue that the extreme weightings in sample efficient portfolios are due to the dominance of a single factor in equity returns. This makes it easy to diversify on subsets to reduce residual risk, while weighting the subsets to reduce factor risk simultaneously. The latter involves taking extreme positions. This behavior seems unlikely to be attributable to sampling error.

Municipal bonds trade in decentralized broker-dealer markets, and are underpriced when issued, but unlike equities the average price rises slowly over several days. Newly issued municipal bonds have high levels of price dispersion and the average price rises because the mix of trade sizes changes over time. While large trades occur close to the reoffering price, small trades occur between the reoffering price to as much as 5% above the reoffering price. Using a mixed-distribution model we quantify the losses uninformed traders or issuers give up to broker-dealers.

[Municipal bonds trade in opaque, decentralized broker-dealer markets in which price information is costly to gather. We analyze a database of trades between broker-dealers and customers in municipal bonds. These data were only released to the public with a lag; the market was opaque. Dealers earn lower average markups on larger trades, even though dealers bear a higher risk of losses with larger trades. We estimate a bargaining model and compute measures of dealer's bargaining power. Dealers exercise substantial market power. Our measures of market power decrease in trade size and increase in the complexity of the trade for the dealer.]