Portfolio choice in Mexico

We study a comprehensive dataset of more than 25,000 portfolios from 28 different banks or investment banks in Mexico during the period from September 2008 – August 2009. Some of these portfolios are administered by an external advisor and/or contain motivated assets – assets bought by a bank's client for whom the bank is also the underwriter. We find that portfolios containing motivated assets underperform. These assets usually are allocated to wealthy retail investors, who are less likely to have an external advisor since their account services generally include an internal advisor. Mexican investors’ portfolios are under-diversified and have a significant home bias. External advisors do not seem to improve the performance of a portfolio during the period studied. However, they do help to reduce the home bias and increase a portfolio's diversification.