What is a bond fund?
"As Michael Pryor answered, a bond fund is a mutual fund that invests in bonds. I'd also consider an ETF based on bonds to be a bond fund, but I'm not sure that all investors would consider these as ""bond funds"". Not all bond funds are the same -- just like stock funds. You can classify bond funds based on the issuer of the bonds: You can also classify funds based on the time to maturity: In general, bond funds have lower risk and lower expected return than stock funds. Sometimes bond funds have price movements that are not tightly correlated to the price movements in the equity markets. This can make them a decent hedge against declines in your equity investments. See Michal Pryor's answer for some info on how you can get tax free treatment for your bond fund investments." "I used the term ""bond fund"" to mean a mutual fund which invests in bonds. Vanguard has a list.  If you live in PA, OH, MA, FL, CA, NJ, or NY there are tax free funds you can invest in on that list." A mutual fund that purchases bonds is a bond fund.     Bond funds are considered to be less risk than a traditional stock mutual fund.   The cost of this less risk is that they have earned (on average) less than mutual funds investing in stocks. Sometimes, bonds have different tax consequences than stocks.
Fire your fund manager. There are several passive funds that seek to duplicate the S&P 500 Index returns. They have lower management fees, which will make returns lower than S&P, and they have less risk by following a broadly diversified strategy (versus midcap growing stocks). There's also ETFs, but evidence is growing that they're not as safe as hoped. But here's the deal: the S&P has been on a tear lately. It could be overvalued and what looks like a good investment could start falling again. A possible alternative would be one of the Lifetime funds that seek to perform portfolio adjustment with a retirement decade target; they're fairly new which mostly means nobody knows how they screw you over yet. In theory, this decade structure means the brokerage can execute trading cash for stocks, stocks for bonds, and bonds for cash in house. Buy a fund of bonds, there are plenty and are registered on your stockbroker account as 'funds' rather than shares. Otherwise, to the individual investor, they can be considered as the same thing. Funds (of bonds, rather than funds that contain property or shares or other investments) are often high yield, low volatility. You buy the fund, and let the manager work it for you. He buys bonds in accordance to the specification of the fund (ie some funds will say 'European only', or 'global high yield' etc) and he will buy and sell the bonds regularly. You never hold to maturity as this is handled for you - in many cases, the manager will be buying and selling bonds all the time in order to give you a stable fund that returns you a dividend. Private investors can buy bonds directly, but its not common.  Should you do it? Up to you. Bonds return, the company issuing a corporate bond will do so at a fixed price with a fixed yield. At the end of the term, they return the principal. So a 20-year bond with a 5% yield will return someone who invests £10k, £500 a year and at the end of the 20 years will return the £10k. The corporate doesn't care who holds the bond, so you can happily sell it to someone else, probably for £10km give or take. People say to invest in bonds because they do not move much in value. In financially difficult times, this means bonds are more attractive to investors as they are a safe place to hold money while stocks drop, but in good times the opposite applies, no-one wants a fund returning 5% when they think they can get 20% growth from a stock. ETFs are just like any other mutual fund; they hold a mix of assets described by their prospectus. If that mix fits your needs for diversification and the costs of buying/selling/holding are low, it's as worth considering as a traditional fund with the same mix. A bond fund will hold a mixture of bonds. Whether that mix is sufficiently diversified for you, or whether you want a different fund or a mix of funds, is a judgement call. I want my money to take care of itself for the most part, so most of the bond portion is in a low-fee Total Bond Market Index fund (which tries to match the performance of bonds in general). That could as easily be an ETF, but happens not to be. John Bogle never said only buy the S&P 500 or any single index Q:Do you think the average person could safely invest for retirement and   other goals without expert advice -- just by indexing? A: Yes, there is a rule of thumb I add to that. You should start out   heavily invested in equities. Hold some bond index funds as well as   stock index funds. By the time you get closer to retirement or into   your retirement, you should have a significant position in bond index   funds as well as stock index funds. As we get older, we have less time   to recoup. We have more money to protect and our nervousness increases   with age. We get a little bit worried about that nest egg when it's   large and we have little time to recoup it, so we pay too much   attention to the fluctuations in the market, which in the long run   mean nothing. How much to pay Q: What's the highest expense ratio that one should pay for a   domestic equity fund? A: I'd say three-quarters of 1 percent maybe.   Q: For an international fund?  A: I'd say three-quarters of 1 percent.   Q: For a bond fund? A: One-half of 1 percent. But I'd shave that a little bit. For   example, if you can buy a no-load bond fund or a no-load stock fund,   you can afford a little more expense ratio, because you're not paying   any commission. You've eliminated cost No. 2.... In the strictest sense, there are bills,notes, and bonds, named when issued based on their time to maturity. Even though it's called a bond ETF it may have a duration short enough to be made of T-bills, less than a year to maturity.  Simply put, for bonds, risk comes from the duration, time to maturity. It's worth pointing out that a bulk of the bond market is institutional investors (read: large corporations and countries). For individuals, it's very easy to just put your cash in a checking account.  Checking accounts are insured and non-volatile.  But what happens when you're GE or Apple or Panama?   You can't just flop a couple billion dollars in to a Chase checking account and call it a day.  Although, you still need a safe place to store money that won't be terribly volatile.  GE can buy a billion dollars of treasury bonds.  Many companies need tremendous amounts of collateral on hand, amounts far in excess of the capacity of a checking account; those funds are stored in treasuries of some sort. Separately, a treasury bond is not a substitute investment for an S&P index fund.  For individuals they are two totally different investments with totally different characteristics.  The only reason an individual investor should compare the return of the S&P against the readily available yield of treasuries is to ensure the expected return of an equity investment can sufficiently pay for the additional risk. "MBS is a fairly general term ""Mortgage Backed Securities"" which simply means that the bond is collateralized with mortgages.  Pass throughs are a type of MBS that is untranched: all bond holders of the deal are receiving the same interest and principal payments, there is no senior or subordinate class of bonds.   Agency passthroughs bond holders receive any principal and interest payments paid by the loans in the pool, minus a slice of the interest payment that pays billing and insurance fees (servicing and guarantee fees, usually a .5% slice of the mortgage interest rate).  On agency product (including Ginnies), if a loan defaults it will be bought out of the pool, with the bondholder receiving all of the expected principal and any interest due on the loan.  Agency deals with different classes of bonds are usually called REMICs.  Passthrough may also be split into  principal-only (PO) and interest-only (IO) pieces.   There is also a huge forward market in soon-to-be-issued passthroughs called the TBA market.  Ginnie Mae has two slightly different programs referred to as Ginnie I and Ginnie II.  Ginnie also has commercial and construction loan financial products.  Freddie and Fannie have the same type of financial products as Ginnie, but there are differences in the sort of loans that Ginnie has vs the other agencies, as well as subtle minor differences between the contract terms of the securities.  Ginnie is also more explicitly guaranteed by the federal government.  You may want to look at:  http://www.ginniemae.gov/index.asp (especially the ""For Investors"" and ""For Issuers"" sections.)  Wikipedia's MBS may be more clear than my description: http://en.wikipedia.org/wiki/Mortgage-backed_security#Types" Bond ETFs are just another way to buy a bond mutual fund.  An ETF lets you trade mutual fund shares the way you trade stocks, in small share-size increments.  The content of this answer applies equally to both stock and bond funds. If you are intending to buy and hold these securities, your main concerns should be purchase fees and expense ratios.  Different brokerages will charge you different amounts to purchase these securities.  Some brokerages have their own mutual funds for which they charge no trading fees, but they charge trading fees for ETFs.  Brokerage A will let you buy Brokerage A's mutual funds for no trading fee but will charge a fee if you purchase Brokerage B's mutual fund in your Brokerage A account. Some brokerages have multiple classes of the same mutual fund.  For example, Vanguard for many of its mutual funds has an Investor class (minimum $3,000 initial investment), Admiral class (minimum $10,000 initial investment), and an ETF (share price as initial investment).  Investor class has the highest expense ratio (ER).  Admiral class and the ETF generally have much lower ER, usually the same number.  For example, Vanguard's Total Bond Market Index mutual fund has Investor class (symbol VBMFX) with 0.16% ER, Admiral (symbol VBTLX) with 0.06% ER, and ETF (symbol BND) with 0.06% ER (same as Admiral).  See Vanguard ETF/mutual fund comparison page.  Note that you can initially buy Investor class shares with Vanguard and Vanguard will automatically convert them to the lower-ER Admiral class shares when your investment has grown to the Admiral threshold. Choosing your broker and your funds may end up being more important than choosing the form of mutual fund versus ETF.  Some brokers charge very high purchase/redemption fees for mutual funds.  Many brokers have no ETFs that they will trade for free.  Between funds, index funds are passively managed and are just designed to track a certain index; they have lower ERs.  Actively managed funds are run by managers who try to beat the market; they have higher ERs and tend to actually fall below the performance of index funds, a double whammy. See also Vanguard's explanation of mutual funds vs. ETFs at Vanguard. See also Investopedia's explanation of mutual funds vs. ETFs in general.