Bonds have higher yields then stocks. Bond funds have higher yields then stock funds. This means more current income for you. Bonds and bond funds are safer then stocks and stock funds, according to conventional wisdom. Bonds fluctuate less in value. That's good, too. So what's wrong with this picture? The interest paid on bonds doesn't grow (they're called fixed income securities for a reason), nor does their principal value. As a matter of fact, the real value of their principal declines over time due to inflation.
Now, before you jump all over me, yes, there are inflation-adjusted Treasury securities that increase in value with inflation and floating-rate bank loan funds whose yield should increase if interest rates go up (although, bank loan funds are much riskier than Treasuries). Also, you can realize a (usually modest) gain in principal value if you buy a bond at less then its face value and hold it until maturity.
There are some managers who through astute analysis, forecasting and trading, add value and outperform a simple buy and hold strategy. However, superior relative performance becomes harder to achieve as you go up in quality, think: High yield ("junk bonds") at one end of the scale and U.S. Treasuries at the other. The same is true for maturities. There's not much a manager can do to create relative value with short term bonds. Value can be created by correctly forecasting (good luck!) interest rates and buying, or selling, long term bonds or through astute credit analysis to determine which companies financial strength will improve, leading to a rating upgrade (if you can do this, you can also pick stocks that will go up in value).
Bond funds do have a place in your portfolio. It's always wise to have a cushion for unforeseen expenses or just to be able to take advantage of an opportunity in the market or elsewhere. If you're going to need cash at a certain time for events such as buying a house, college education, or the like, having the safety and certainty of a bond fund is a smart investment. Caveat: if you need funds at a not too distant date don't speculate with a risky (non-investment grade) bond fund, you'll be unpleasantly surprised with its volatility.
I fear that too many investors put too much money in bond funds and do so too soon in their investing careers. The income may be reassuring, or even seductive, but the limited appreciation and cumulative effects of inflation must be considered. The current income is nice but neither the income, not the principal increase over time, absent a good fund manger. So what's an investor to do?
Find a good conservative mutual fund which invests in high quality dividend paying stocks. Why? Because dividends paid by good companies tend to increase over time. Take Bank of America, for example. (I'm using a stock rather than a mutual fund for this illustration because it avoids having to talk about purchases, sales and capital gains distributions.) In 1997, Bank America paid a $.70 per share dividend. If you bought the stock near its high for that year, you paid $40 per share. Today, Bank of America pays a $2.24 dividend and its stock sells for around $50. Notice, the dividend has increased 3x in the past ten years. The price appreciation hasn't been nearly as exciting, but it has kept pace with inflation.
There are a lot of stocks out there, like Bank America, which increase their dividend every (or almost every) year. The investor who bought Bank of America stock in my example has an investment currently yielding 5.6% and I would expect the yield to continue increasing. You can find many mutual funds that invest in high quality, dividend growing stocks. Start by looking at Big Cap Value funds. Many such funds have the word income or dividend in their name.
There are lots of good reasons to invest in bond funds, but if you have a time horizon of ten years or more, you'll be better off investing in a high quality equity mutual fund. You'll end up with more principal and more income.
