Building a Diversified Portfolio
Practical portfolio construction across asset classes, and Malkiel's take on international diversification and real estate.
Beyond the core stocks-versus-bonds allocation covered in the life-cycle chapter, Malkiel walks through building out a fuller diversified portfolio — adding international stocks alongside domestic ones, since different countries' equity markets don't move in perfect lockstep, and real estate (through REITs, real estate investment trusts, rather than direct property ownership for most investors) as a further diversifying asset class with somewhat different return drivers than either stocks or bonds.
The organizing principle across all of it is the same one from earlier in the book: assets whose returns aren't perfectly correlated with each other reduce a portfolio's overall volatility for a given expected return, even when none of the individual assets is picked for any special insight into its own future performance — the diversification benefit comes from the combination, not from any single component being individually superior.
| Asset class | Role in the portfolio |
|---|---|
| Domestic stocks | Core long-run growth engine |
| International stocks | Diversification — doesn't move in perfect lockstep with domestic markets |
| Bonds | Lower volatility, income, and a shock absorber against stock declines |
| REITs | Real-estate exposure with different return drivers than stocks or bonds, without direct property ownership |
Malkiel pairs the diversified-allocation recommendation with periodic rebalancing — selling a portion of whichever asset class has grown to be overweight relative to the target allocation, and buying more of whichever has become underweight, restoring the original target mix on a regular schedule (annually, for instance). The behavioral value of this discipline is that it forces a mechanical version of "buy low, sell high" — trimming an asset class after it has risen and adding to one after it has fallen — without requiring the investor to make any active judgment call about which asset class is about to do better, sidestepping the same behavioral traps covered earlier in this course.
- A fuller diversified portfolio extends beyond domestic stocks and bonds to include international stocks and real estate (via REITs).
- The diversification benefit comes from combining assets whose returns aren't perfectly correlated, not from any single asset class being individually superior.
- Periodic rebalancing back to a target allocation mechanically enforces buying low and selling high without requiring active market-timing judgment.