With interest rates near historical lows, some investors may be anxious about a possible rate climb and its potential impact on their fixed income investments. Rising interest rates typically cause existing bonds to lose value. While investors might hold short-term instruments to manage this risk, an interest rate decline could spoil this strategy by forcing investors to reinvest in lower yields when their short-term instruments mature.

Rate movements in either direction affect portfolio returns. This is true in any market environment, regardless of the current rate level. The larger question is how to manage the risk. As you read the financial headlines and evaluate your current fixed income exposure, it may be helpful to consider these principles about fixed income investing:

Interest rate movements are unpredictable.

Academic research offers strong evidence that the bond market is efficient, and that bond prices and interest rates are not predictable over the short term.¹ This uncertainty is reflected in the often-contradictory interest rate forecasts offered by economists, analysts, and other market watchers.²

Even when the experts share similar views on the direction of the economy and credit markets, reality often proves them wrong. Last year’s Wall Street Journal forecasting survey offers a recent example.³ Among fifty economic forecasters surveyed in 2009, forty-three expected the ten-year US Treasury note yield to move higher over the next year, with an average estimate of a 4.13% yield. Only two respondents predicted rates to fall below 3.00%. The ten-year Treasury yield slumped to 2.95% on June 30, 2010, and rates on thirty-year mortgages fell to their lowest level since Fannie Mae began tracking them in 1971.

Today’s bond prices already reflect expectations for tomorrow’s business conditions and inflation, and these expectations can change quickly in response to new information. This new information is unknowable. Investors who accept market efficiency should not be surprised when the credit markets foil the experts. If prices were easy to forecast, you should find a host of fixed income managers with market-beating returns. But most of them underperform their respective benchmarks over longer time periods.⁴

Since no one has a reliable method for determining whether interest rates will rise or fall in the near future, investors should avoid making fixed income decisions based on a forecast, media coverage, or their own hunches.

Pursuing higher expected returns requires more risk taking.

The strong link between risk and return appears in all properly functioning capital markets. When investing in stocks, bonds, or other assets, investors must accept more risk to pursue a higher potential return.

In the fixed income markets, earning a return above short-term government instruments is usually a function of assuming more term and credit risk. Term risk refers to a bond’s maturity, and credit risk refers to the creditworthiness or default potential of the borrower. Bonds with longer maturities and lower credit quality are usually considered riskier and have offered higher yields and returns to compensate investors for higher risk.

On the term side, investors who commit their capital for longer periods of time are exposed to the amplified effects of changing interest rates. Bond prices and interest rates move in the opposite direction: When rates rise, the value of an existing bond declines; when rates fall, bond values rise. The market adjusts the price to match the yield available on a new instrument. The longer the bond’s maturity, the greater the price adjustment for a particular interest rate change. A long-term bond is more exposed to rate changes than a short-term instrument, and usually (but not always) offers a higher yield to compensate investors for the extra risk. Also, lower-coupon bonds are more affected by interest rate changes than higher-coupon bonds. For example, if rates move 1%, a bond that pays 3% will experience a greater gain or loss than one paying 5%.

On the credit risk side, the government is considered the strongest borrower in the market, so it has a lower cost of capital relative to other issuers. The most creditworthy companies are considered relatively safe, but they must still offer a higher rate than the government to compensate investors for taking more default risk. The weaker a corporate borrower’s financial condition, the more it must pay in yield to attract investors. Investors seeking higher returns on the credit spectrum must bear a higher risk of default.⁵

Investment strategy should drive fixed income decisions.

Investors may hold fixed income securities for a variety of reasons—for example, to reduce portfolio volatility, generate income, maintain liquidity, pursue higher returns, or meet a future funding obligation. Each objective may involve a different portfolio approach, or a combination of strategies to manage tradeoffs. For example, investors who want to maximize current income may not be strongly concerned with the effects of short-term price volatility. They may extend maturity or accept slightly lower credit quality when the market offers a yield premium for doing so. On the other hand, investors seeking long-term wealth appreciation may commit most of their portfolio to equities and keep their fixed income investments short term and high quality to buffer the volatility of stocks.

Regardless of your approach, you should know the difference between controlling risk and avoiding it. You cannot eliminate risk, but you can manage your exposure by diversifying across maturities, industries, countries, and currencies to reduce the impact of rates, inflation, currency fluctuations, and other risks. Your decision to take more term and default risk may depend on the current state of the yield curve and credit spread.

Many factors influence the direction of interest rates and performance in the bond markets, and these are too complex for anyone to reliably predict. Rather than placing your faith in the experts or reacting to economic news, manage your fixed income component from a portfolio perspective. Your strategy should reflect your overall investment goals, risk tolerance, and other personal financial considerations. This is a solid approach to managing your portfolio in an uncertain interest rate market.

1. Eugene F. Fama, “The Information in the Term Structure,” Journal of Financial Economics 13, no. 4 (December 1984): 509-528. Also: Robert R. Bliss and Eugene F. Fama, “The Information in Long-Maturity Forward Rates,” American Economic Review 77, no. 4 (September 1987): 680-692.

2. Mark Gongloff, “Two Treasury Forecasts: a Grand Canyon-Size Gap,” Wall Street Journal, April 10, 2010.

3. Wall Street Journal Forecasting Survey, www.wsj.com, accessed July 7, 2010.

4. Christopher R. Blake, Edwin J. Elton, and Martin J. Gruber, “The Performance of Bond Mutual Funds,” Journal of Business 66, no. 3 (July 1993): 371-403. Also see Standard & Poor’s Indices Versus Active (SPIVA) Scorecard for the US, Canada, Australia, and Europe (http://www.standardandpoors.com/indices/spiva/en/us).

5. The yield curve plots the current relationship between rates and maturity, and the credit spread plots the risk-return relationship across the range of credit qualities. The curves offer a current snapshot of how markets are pricing term and credit exposure.

Choosing a basic stock-bond mix is an important first step in portfolio design. Although the decision may appear simple, it can have a profound impact on your wealth. 

Portfolio theory explains the value of making a deliberate, strategic decision about the proportion of stocks versus bonds to hold in a portfolio. This decision has roots in the “separation theorem,” which was proposed by Nobel laureate James Tobin in the late 1950s.¹ The separation theorem proposes that all investors face two important decisions: (1) deciding how much risk to take, and then (2) forming a portfolio of “risky” assets (equities) and “less risky” assets (fixed income) to achieve this risk exposure.  

Your stock-bond decision implements this risk position. 

The Rationale

The theorem proposes that all investors who are willing to take stock risk should begin with a diversified market portfolio. Each investor then can dial down total risk in the portfolio by adding fixed income to the mix. The greater the bond allocation relative to stocks, the less risky the portfolio and the lower the total expected return; the greater the stock allocation relative to bonds, the higher the portfolio’s expected return and risk.  

Investors who want to take even more risk than the market can increase exposure through borrowing on margin and/or tilting the stock portfolio toward asset groups that offer higher expected returns for higher risk. 

So, how does one confidently allocate between stocks and bonds? A common method is to evaluate model portfolios along the risk-return spectrum. A riskier portfolio holds 100% stocks, and the least volatile portfolio holds 100% bonds. Between these extremes lie standard stock-bond allocations, such as 80%-20%, 60%-40%, 40%-60%, and 20%-80%.² Then you compare the average annualized return and volatility (standard deviation) of each model portfolio for different periods, such as one, three, five, ten, and twenty years. Volatility is one of several risk measures investors may want to consider. With this in mind, the analysis should feature average returns, as well as best- and worst-case returns for the various periods. 

While this technique relies on historical performance that may not repeat in the future, and does not consider various investment costs, it may help you think about the risk-return tradeoff and visualize the range of potential outcomes based on the aggressiveness of your strategy. 

Refining Your Stock Allocation

After establishing the basic stock-bond mix, investors turn their attention to refining the stock allocation, which is where the best opportunities to refine the risk-return tradeoff are found.  Investors who are comfortable with higher doses of equity risk can overweight or “tilt” their allocation toward riskier asset classes that have a history of offering average returns above the market. Research published by Eugene Fama and Kenneth French found that small cap stocks have had higher average returns than large cap stocks, and value stocks have had higher average returns than growth stocks. By holding a larger portion of small cap and value stocks in a portfolio, an investor increases the potential to earn higher returns for the additional risk taken.  

The final step in refining the stock component is to diversify globally. By holding an array of equity asset classes across domestic and international markets, investors can reduce the impact of underperformance in a single market or region of the world. Although the markets may experience varying levels of return correlation, this diversification can further reduce volatility in a portfolio, which translates into higher compounded returns over time. 

Fixed Income Strategies

Research shows that two risk factors—maturity and credit quality—account for most of the average return differences in diversified bond portfolios. Long-term bonds and lower-quality corporate bonds typically offer higher average yields to compensate investors for taking more risk. But keep in mind that these premiums are considerably lower than the market, size, and value premiums documented in the equity world. 

Investors generally hold fixed income to either (1) reduce overall portfolio volatility, or (2) generate a reliable income stream. These objectives typically lead to different investment decisions. The first approach, volatility reduction, is an application of separation theorem (i.e., hold equities for higher return and use fixed income to temper portfolio volatility). Rather than increasing risk to maximize yield, these investors want to hold fixed income securities that are lower risk. Certain fixed income asset groups are better suited for this strategy. 

With this in mind, some long-term investors may seek to earn higher expected returns by shifting risk to the equity side of their portfolio. With an eye to minimize maturity and credit risk, they hold short-term, high-quality debt instruments that have historically offered lower yields with much lower volatility. 

The second purpose for holding bonds is to generate reliable cash flow. Income-oriented investors, including retirees, pension plans, and endowments, may not worry as much about short-term volatility in their bond portfolio. Their priority is to meet a specific funding obligation in the future. Consequently, they design a portfolio around bonds and accept more volatility in hope of earning higher yields, which they pursue by holding bonds with longer maturities and/or lower credit quality. 

Whether investing for total long-term return or for income, a portfolio should be diversified across issues and global markets to avoid uncompensated risk from specific issuers and to capture differences in yield curves around the world.  

Summary

The stock-bond decision drives a large part of your portfolio’s long-term performance. During portfolio design, evaluating different stock-bond combinations can help you visualize the risk-return tradeoff as you consider the range of potential outcomes over time. Once you determine a mix, it can guide more detailed choices of asset classes to hold in the portfolio. And as your appetite for risk shifts over time, you can revisit the mix to estimate how shifting your portfolio mix may impact your wealth accumulation goals in the future.  

Endnotes

¹ James Tobin, “Liquidity Preference as Behavior Towards Risk,” The Review of Economic Studies 25, no. 2 (February 1958): 65-86.  

² The basic stock component may be reflected by the S&P 500 Index, or preferably, by a broader market proxy, such as the CRSP 1-10 Index. The CRSP 1-10 Index is a market capitalization weighted index of all stocks listed on the NYSE, Amex, NASDAQ, and NYSE Arca exchanges. The S&P 500 Index offers a proxy of the large cap US equities market. The fixed income component may be represented by an index of short-term US government securities or government and corporate bonds.   

The information presented above was prepared by Dimensional Fund Advisors, a non-affiliated third party.

 Disclosures

Stock is the capital raised by a corporation through the issue of shares entitling holders to an ownership interest of the corporation. A bond is a loan that an investor makes to a corporation, government, federal agency, or other organization. Also known as debt or fixed income securities, most types of bonds pay interest based on a regular, predetermined coupon rate that is set when the bond is issued. 

Although investors may form their expectations from the past, there is no assurance that future investment results will model historical performance.  

Indexes are not available for direct investment. Their performance does not reflect the expenses associated with the management of an actual portfolio. Past performance is not a guarantee of future results. 

Stocks offer a higher potential return as compensation for bearing higher risk. However, this premium is not a certainty and investors should not expect to consistently receive higher returns from stocks. In fact, market history shows extended periods when stocks did not outperform bonds.  

Diversification neither assures a profit nor guarantees against loss in a declining market. 

A bond portfolio designed for income also carries significant risks, including default and term risk, call risk, and purchasing power (inflation) risk. Foreign securities also are exposed to currency movements.