Diversification is a risk management strategy that mixes a wide variety of investments within a portfolio. A diversified portfolio contains a mix of distinct asset types and investment vehicles in an attempt at limiting exposure to any single asset or risk. The rationale behind this technique is that a portfolio constructed of different kinds of assets will, on average, yield higher long-term returns and lower the risk of any individual holding or security.
The Basics of Diversification
Diversification strives to smooth out unsystematic risk events in a portfolio, so the positive performance of some investments neutralizes the negative performance of others. The benefits of diversification hold only if the securities in the portfolio are not perfectly correlated, that is, they respond differently, often in opposing ways, to market influences.
Studies and mathematical models have shown that maintaining a well-diversified portfolio of 25 to 30 stocks yields the most cost-effective level of risk reduction. Investing in more securities generates further diversification benefits, albeit at a drastically smaller rate.
KEY TAKEAWAYS
Diversification is a strategy that mixes a wide variety of investments within a portfolio.
Portfolio holdings can be diversified across asset classes and within classes, and also geographically—by investing in both domestic and foreign markets.
Diversification limits portfolio risk but can also mitigate performance, at least in the short term.
Diversification by Asset Class
Fund managers and investors often diversify their investments across asset classes and determine what percentages of the portfolio to allocate to each. Classes can include:
Stocks— shares or equity in a publicly-traded company
Bonds — government and corporate fixed-income debt instruments
Real estate — land, buildings, natural resources, agriculture, livestock, and water and mineral deposits
Exchange-traded funds (ETFs)— a marketable basket of securities that follow an index, commodity, or sector
Commodities — basic goods necessary for the production of other products or services
Cash and short-term cash-equivalents (CCE)— Treasury bills, certificate of deposit (CD), money market vehicles, and other short-term, low-risk investments
They will then diversify among investments within the assets classes, such as by selecting stocks from various sectors that tend to have low return correlation, or by choosing stocks with different market Capitalization. In the case of bonds, investors can select from investment-grade corporate bonds, U.S. Treasuries, state and municipal bonds, high-yield bonds, and others.
Foreign Diversification
Investors can reap further diversification benefits by investing in foreign securities because they tend to be less closely correlated with domestic ones. For example, forces depressing the U.S. economy may not affect Japan’s economy in the same way. Therefore, holding Japanese stocks gives an investor a small cushion of protection against losses during an American economic downturn.
Diversification and the Retail Investor
Time and budget constraints can make it difficult for non-institutional investors—i.e., individuals—to create an adequately diversified portfolio. This challenge is a key reason why mutual funds are so popular with retail investors. Buying shares in a mutual fund offers an inexpensive way to diversify investments.
While mutual funds provide diversification across various asset classes, exchange-traded funds (ETFs) afford investor access to narrow markets such as commodities and international plays that would ordinarily be difficult to access. An individual with a $100,000 portfolio can spread the investment among ETFs with no overlap.
Disadvantages of Diversification
Reduced risk, a volatility buffer: The pluses of diversification are many. However, there are drawbacks, too. The more holdings a portfolio has, the more time-consuming it can be to manage—and the more expensive, since buying and selling many different holdings incurs more transaction fees and brokerage commissions. More fundamentally, diversification’s spreading-out strategy works both ways, lessening both the risk and the reward.
Say you’ve invested $120,000 equally among six stocks, and one stock doubles in value. Your original $20,000 stake is now worth $40,000. You’ve made a lot, sure, but not as much as if your entire $120,000 had been invested in that one company. By protecting you on the downside, diversification limits you on the upside—at least, in the short term. Over the long term, diversified portfolios do tend to post higher returns (see example below).
Pros
Reduces portfolio risk
Hedges against market volatility
Offers higher returns long-term
Cons
Limits gains short-term
Time-consuming to manage
Incurs more transaction fees, commissions
Diversification and Smart Beta
Smart beta strategies offer diversification by tracking underlying indices but do not necessarily weigh stocks according to their market cap. ETF managers further screen equity issues on fundamentals and rebalance portfolios according to objective analysis and not just company size. While smart beta portfolios are unmanaged, the primary goal becomes outperformance of the index itself.
For example, as of March 2019, the iShares Edge MSCI USA Quality Factor ETF holds 125 large- and mid-cap U.S. stocks. By focusing on return on equity (ROE), debt-to-equity (D/E) ratio, and not solely market cap, the ETF has returned 90.49% cumulatively since its inception in July 2013. A similar investment in the S&P 500 Index grew by 66.33%.
