Households’ Portfolio Diversification

This paper performs an efficiency analysis of households portfolios based on the comparison of observed portfolios with the mean-variance frontier of assets returns. Data on household portfolios are drawn from the 2001 Centro Einaudi survey, a representative sample of the Italian population with at least a bank account. We find that most households’ portfolios are extremely close to the efficient frontier once we explicitly take into account no short-selling constraints, while the null hypothesis of efficiency is rejected for all portfolios if we don’t consider these constraints.

Equity Portfolio Diversification

In this paper we examine the portfolios of more than 40,000 equity investment accounts from a large discount brokerage during a six year period (1991-96) in recent U.S. capital market history. Using the historical performance for the equities in these accounts, we find that a vast majority of investors in our sample are under-diversified. Even accounting for the likelihood we have selected on speculators, the magnitude of the diosyncratic risk taken by investors in our sample is surprising. Investors are aware of the benefits of diversification but they appear to adopt a 'naive' diversification strategy where they form portfolios without giving proper consideration to the correlations among the stocks. Over time, the degree of diversification among investor portfolios has improved but these improvements result primarily from changes in the correlation structure of the US equity market. Cross-sectional variations in diversification across demographic groups suggest that investors in low income and non-professional categories hold the least diversified portfolios. In addition, we find that young, active investors are over-focused and hold under-diversified portfolios. Overall, our results indicate that investors realize the benefits of diversification but they face a daunting task of 'implementing' and maintaining a well-diversified portfolio.

Portfolio Diversification in Europe

Have the euro and accompanying measures of financial integration had a discernable impact on the degree of diversification of European investors? This is an empirical question that this paper tries to answer by exploring four alternative avenues. First we focus on the final outcome: If European investors are indeed better diversified, their consumption should be increasingly correlated. Second we check more directly what is known about the composition of Europeans’ portfolios. A third perspective focuses on the evolution of returns and prices. If indeed European investors are attempting to exploit new arbitrage opportunities opened up by the euro and European financial integration, then it is likely that these behavioral changes will be matched by significant changes in returns or in the nature of the return generating process. Finally, we explore the possibility that the answer to our question may be better revealed by examining the changes that have taken place in the investment process itself.Risk sharing, Portfolio holdings, financial market integration, cross sectional dispersion

Risk minimization and portfolio diversification

We consider the problem of minimizing capital at risk in the Black-Scholes setting. The portfolio problem is studied given the possibility that a correlation constraint between the portfolio and a financial index is imposed. The optimal portfolio is obtained in closed form. The effects of the correlation constraint are explored; it turns out that this portfolio constraint leads to a more diversified portfolio

Financial Literacy and Portfolio Diversification

In this paper we focus on poor financial literacy as one potential factor explaining lack of portfolio diversification. We use the 2007 Unicredit Customers’ Survey, which has indicators of portfolio choice, financial literacy and many demographic characteristics of investors. We first propose test-based indicators of financial literacy and document the extent of portfolio under-diversification. We find that measures of financial literacy are strongly correlated with the degree of portfolio diversification. We also compare the test-based degree of financial literacy with investors’ self-assessment of their financial knowledge, and find only a weak relation between the two measures, an issue that has gained importance after the EU Markets in Financial Instruments Directive (MIFID) has required financial institutions to rate investors’ financial sophistication through questionnaires.Financial literacy, Portfolio diversification

Price Discrimination As Portfolio Diversification

A seller seeking to sell an indivisible object can post (possibly different) prices to each of n buyers. Buyers' valuations are private information and drawn independently from the same distribution. If the seller can choose who to sell to in the event there are several willing buyers, her optimal strategy is to post different prices to different buyers. For some distributions, price discrimination may be profitable even if excess demand must be resolved through a uniform lottery.

Can Mergers in Europe Help Banks Hedge Against Macroeconomic Risk

European integration, risk sharing, regional specialization, portfolio diversification.

Portfolio Diversification and City Agglomeration

We relate the degree of investor portfolio focus to the broader urban economic context of the household. Using a detailed panel of investors in Sweden over the period 1995 to 2000, we find that the level of investor diversification, as measured by number of stocks in the portfolio and by the average correlation among holdings, is partially explained by city industrial characteristics. We find that rural portfolios are more diversified than urban portfolios and that portfolio diversification is characterized by factors associated with urban growth. We consider a number of theories to explain investor focus, including behavioral biases, real and perceived informational advantage, local social competition and hedging of non-tradable risk. We find little evidence to support social and hedging motives to explain the lack of portfolio diversification, and some evidence in favor of perceived informational advantage in an urban setting. We attribute this evidence as support for the broader 'knowledge spillover' processes documented in the recent urban economics literature. Portfolio effects may be added to the list of factors that define and differentiate urbanism.