Portfolio Construction for Taxable Investors
Scott J. Donaldson, CFA,CFP, and Frank A. Ambrosio, CFA, Vanguard Investment Counseling & Research (2007)Executive summary. Most investment portfolios are designed to meet a specific future financial need—either a single goal or a multifaceted set of objectives. To reach those goals and objectives, a disciplined method of portfolio construction must be established that balances the potential risks and returns of various types of investments. This paper reviews various aspects of our research involving five major investment decisions that need to be made, in successive order, in the portfolio construction process. The decisions are:
Asset allocation—Choosing asset-class weights: equities, fixed income, cash, and so on.
Sub-asset allocation—Choosing investments within an asset class, such as U.S. or international equities; or large-, mid-, or small-capitalization equities.
Active and/or passive allocations—Choosing indexed and/or actively managed assets.
Asset location—Deciding on the placement of investments in taxable and/or tax-advantaged accounts.
Manager selection—Choosing individual managers, funds, or securities to fill allocations.
The top-down order in which these decisions are made is important in establishing a well-constructed portfolio. Many investors use a bottom-up approach, placing more emphasis on manager/security selection or sub-asset allocation (based on an investment’s recent returns) than on asset allocation, the most important portfolio decision. However, in using a bottom-up approach, the selection of the investments—potentially the more uncertain part of portfolio construction—would then determine the more important part—the overall asset allocation. After deciding the asset allocation of the portfolio, it is important to keep in mind that broad diversification, with exposure to all parts of the stock and bond markets, is a powerful strategy for managing portfolio risk. Diversification across asset classes reduces a portfolio’s exposure to the risks common to an entire asset class. Diversification within asset classes reduces a portfolio’s exposure to the risks associated with a particular company, sector, or market. This diversification can be achieved through index and/or actively managed investment strategies. The decision to purchase certain investments within either tax-advantaged and/or taxable accounts, known as asset location, is a valuable tool to increase potential after-tax returns. This can be achieved by placing tax efficient assets in taxable accounts and tax inefficient assets in tax-advantaged accounts. Selecting specific investments to represent the various market segments should come last. A common error in portfolio construction is that of choosing specific investments that may appear to be worthwhile individually, but make little sense when combined in a portfolio. In the end, this collection of investments does not necessarily form a coherent asset allocation or sub-asset allocation that matches the investor’s objectives and risk tolerance.