What Is a Bond? Definition, Types, and How Bonds Work
Last updated 04/14/2026 by
Ante Mazalin
Summary:
A bond is a debt security in which an investor lends money to an issuer — a government, municipality, or corporation — in exchange for regular interest payments and the return of the principal at a specified maturity date.
Bonds are categorized by who issues them and by the creditworthiness of the issuer.
- Government bonds: Issued by national governments; U.S. Treasury bonds are considered the lowest-risk bonds available, backed by the full faith and credit of the federal government.
- Municipal bonds: Issued by states, cities, and local agencies; interest is typically exempt from federal income tax, making them valuable to investors in higher tax brackets.
- Corporate bonds: Issued by companies to fund operations or expansion; they pay higher yields than government bonds to compensate for greater credit risk.
- High-yield (junk) bonds: Issued by companies with below-investment-grade credit ratings; they carry the highest default risk and the highest yields.
Bonds are the foundation of fixed income investing — a category that spans everything from ultra-safe U.S. Treasuries to speculative high-yield corporate debt. The U.S. corporate bond market alone totals approximately $10.7 trillion in outstanding debt, according to SIFMA, making bonds one of the largest and most actively traded asset classes in the world.
For most investors, bonds serve two roles: generating predictable income and reducing the volatility of a portfolio that also holds stocks. Understanding how they’re priced, what drives their yields, and where they fit against other investments clarifies why they belong in a diversified portfolio.
How a bond works
When you buy a bond, you are lending money to the issuer. The issuer promises to pay you interest at a fixed rate on a regular schedule — typically every six months — and to return your original principal in full when the bond matures.
The relationship is formalized in a bond indenture, a legal contract that specifies every term of the arrangement. SuperMoney’s entry on bond covenants covers the protective clauses issuers agree to as part of that contract.
Key bond terms
Every bond is defined by four core terms. Knowing them is required to compare bonds or evaluate any fixed income investment.
- Face value (par value): The principal amount the issuer will repay at maturity — typically $1,000 per bond. This is also the amount on which the coupon rate is calculated.
- Coupon rate: The annual interest rate the bond pays, expressed as a percentage of face value. A bond with a $1,000 face value and a 5% coupon rate pays $50 per year, usually in two $25 semi-annual installments.
- Maturity date: The date on which the issuer repays the face value and interest payments stop. Bonds are classified as short-term (under 2 years), intermediate-term (2–10 years), or long-term (10+ years) based on their maturity.
- Yield: The actual return an investor earns, accounting for both the coupon payments and the price paid for the bond. If you buy a bond at a discount to face value, your yield will be higher than the coupon rate. If you pay a premium, your yield will be lower.
Types of bonds
The bond universe spans issuers at every credit risk level. The main categories differ in who issues them, how they’re taxed, and how much yield they offer to compensate for their risk.
| Type | Issuer | Risk Level | Tax Treatment |
|---|---|---|---|
| U.S. Treasury | Federal government | Lowest | Federal taxable; state/local exempt |
| Agency | U.S. government agencies (Fannie Mae, Freddie Mac) | Very low | Varies by agency |
| Municipal | State and local governments | Low to moderate | Federal tax-exempt; often state-exempt |
| Investment-grade corporate | Companies rated BBB-/Baa3 or higher | Moderate | Fully taxable |
| High-yield (junk) | Companies rated below BBB-/Baa3 | High | Fully taxable |
U.S. Treasury bonds are the benchmark for risk-free investing. Backed by the full faith and credit of the U.S. government, they set the baseline yield against which all other bonds are measured. SuperMoney’s dedicated entry on Treasury bonds covers their specific structures — bills, notes, and bonds — in detail.
High-yield bonds — commonly called junk bonds — are issued by companies with credit ratings below investment grade. Because the probability of default is higher, investors demand significantly more yield to compensate. SuperMoney’s entry on junk bonds covers how they work and when they make sense in a portfolio.
How bond prices and yields work
Bond prices and interest rates move in opposite directions. This inverse relationship is one of the most important concepts in fixed income investing — and one of the most misunderstood.
Here is why it works this way: suppose you own a bond paying a 4% coupon when prevailing interest rates are also 4%. That bond trades at par — its face value. Now suppose rates rise to 6%. Newly issued bonds pay 6%, making your 4% bond less attractive. To sell it, you’d have to offer it at a discount, bringing its effective yield in line with the 6% available elsewhere. The bond’s price falls.
The reverse is equally true: when rates fall, existing bonds with higher coupons become more valuable, and their prices rise.
This relationship has direct consequences for investors:
- If you hold to maturity: Price fluctuations don’t affect you — you collect every coupon payment and receive face value at maturity regardless of what rates do in the interim.
- If you sell before maturity: You are exposed to interest rate risk. Rising rates mean you may sell at a loss relative to what you paid, even if the issuer never defaulted.
- Longer maturities = more sensitivity: A 30-year bond’s price fluctuates far more with interest rate changes than a 2-year bond’s price, because more future payments are being discounted at the new rate.
Duration: measuring interest rate risk
Duration is the standard metric for quantifying a bond’s sensitivity to interest rate changes. It’s expressed in years, but what it actually measures is price change: a bond with a duration of 7 will lose approximately 7% of its market value for every 1 percentage point rise in interest rates — and gain approximately 7% for every 1 point decline.
According to FINRA, a bond with a duration of 10 would lose roughly 10% of its value if rates rose by 1% — versus only 1% for a bond with a 1-year duration. This is why bond investors closely monitor Federal Reserve rate policy: rate hikes reduce the value of existing long-duration bond portfolios directly.
Three factors drive duration higher:
- Longer maturity: More years of future payments to discount at the new rate.
- Lower coupon rate: Less interim cash flow, so more of the total return is tied to the final principal payment — which is further in the future.
- Lower yield: A lower starting yield makes each future payment worth more relatively, increasing sensitivity to changes.
Credit ratings
Credit ratings assess the likelihood that a bond issuer will make all promised payments on time. The three major rating agencies — Moody’s, S&P Global Ratings, and Fitch Ratings — control approximately 95% of the ratings market and use similar but not identical scales.
| S&P / Fitch | Moody’s | Category | Meaning |
|---|---|---|---|
| AAA | Aaa | Investment grade | Highest quality; extremely low default risk |
| AA | Aa | Investment grade | Very high quality; minimal default risk |
| A | A | Investment grade | High quality; low default risk |
| BBB | Baa | Investment grade | Adequate capacity; lowest investment-grade tier |
| BB / B | Ba / B | High yield (junk) | Speculative; elevated default risk |
| CCC and below | Caa and below | High yield (junk) | Substantial default risk to currently in default |
Investment-grade bonds (BBB-/Baa3 or higher) are favored by pension funds, insurers, and conservative investors because many institutions are required by charter or regulation to hold only investment-grade debt.
A rating downgrade from investment grade to junk — called a “fallen angel” — can trigger forced selling by institutional holders, often causing a sharp price drop regardless of the company’s actual financial position.
Pro tip: Credit ratings are backward-looking — agencies rate based on current financial health, not future conditions. During the 2008 financial crisis, many mortgage-backed securities held AAA ratings until they collapsed. Always read beyond the rating: review the issuer’s financials, debt-to-equity ratio, and interest coverage ratio before relying on a rating alone.
Bonds vs. stocks
Bonds and stocks are the two primary building blocks of most investment portfolios. They behave differently under the same market conditions, which is why holding both reduces overall volatility.
- Return profile: Stocks have historically delivered higher long-term returns — around 10% annually for the S&P 500 — while bonds deliver lower but more predictable returns. The Bloomberg U.S. Aggregate Bond Index has returned approximately 4–5% annually over long periods.
- Priority in bankruptcy: Bondholders are creditors — they are paid before stockholders when a company is liquidated. Common stockholders receive whatever is left, which can be nothing.
- Income certainty: Bonds pay a fixed coupon on a defined schedule. Stock dividends are discretionary and can be cut at any time.
- Correlation: Bonds and stocks often (though not always) move in opposite directions. When equity markets sell off, investors frequently move into bonds as a safe haven, pushing bond prices up — providing a cushion to a mixed portfolio.
How to invest in bonds
Bonds can be purchased in several ways, each with different cost and access trade-offs.
- Directly from the issuer: U.S. Treasury bonds can be purchased commission-free through TreasuryDirect.gov at auction. New municipal and corporate bond issues are purchased through underwriting banks at issuance.
- On the secondary market: Existing bonds trade through brokerages, often with a dealer spread (the difference between the buy and sell price) rather than a commission. The bond market is primarily an over-the-counter market — bonds don’t trade on centralized exchanges the way stocks do.
- Through bond mutual funds or ETFs: A bond mutual fund or index fund pools investor money to buy a diversified portfolio of bonds. This is the most accessible approach for most individual investors — it provides instant diversification across dozens or hundreds of issuers with a single purchase and a low minimum investment.
Frequently asked questions
Are bonds safer than stocks?
Generally, yes — but the comparison depends on the specific bond and stock. U.S. Treasury bonds carry effectively zero default risk and low volatility. High-yield corporate bonds carry significant default risk and can be as volatile as stocks during market stress. As a broad category, bonds sit lower on the risk-return spectrum than stocks: they offer more predictable income but less long-term growth potential.
What happens to a bond if the issuer goes bankrupt?
Bondholders are creditors and have priority over stockholders in bankruptcy proceedings. Secured bondholders (backed by specific assets) are paid first, then unsecured bondholders. How much bondholders recover depends on the company’s remaining assets and the type of bond held. In many bankruptcies, senior secured bondholders recover most of their principal while junior bondholders and stockholders recover little or nothing.
Can you lose money on a bond?
Yes, in two main ways. First, if the issuer defaults, you may not receive all promised payments. Second, if you sell a bond before maturity when interest rates have risen, you sell at a market price below what you paid — a capital loss. If you hold to maturity and the issuer doesn’t default, you receive every coupon and the full face value regardless of how prices moved in the interim.
What is the difference between a bond and a note?
The distinction is primarily maturity length. In U.S. Treasury markets specifically, bills mature in one year or less, notes mature in 2 to 10 years, and bonds mature in more than 10 years — up to 30 years. In common usage, “bond” is used as a catch-all term for all fixed income debt securities regardless of maturity.
What does it mean when a bond trades at a discount or premium?
A bond trades at a discount when its market price is below its face value — usually because prevailing interest rates have risen above the bond’s coupon rate, making it less attractive than newly issued bonds. A bond trades at a premium when its price exceeds face value — usually because its coupon rate is higher than current market rates, making it more desirable. In both cases, if held to maturity, the investor receives exactly the face value.
What is a government bond?
A government bond is debt issued by a national government to finance spending. U.S. government bonds (Treasuries) are denominated in U.S. dollars and backed by the government’s taxing authority — making them the global benchmark for risk-free fixed income. Other countries issue their own sovereign bonds, which carry varying degrees of credit risk depending on fiscal health and currency stability.
Key takeaways
- A bond is a loan from an investor to an issuer — the issuer pays a fixed coupon (interest) on a regular schedule and returns the face value at maturity.
- The four core terms that define any bond are face value, coupon rate, maturity date, and yield — understanding all four is required to evaluate and compare bonds.
- Bond prices and interest rates move inversely: when rates rise, existing bond prices fall; when rates fall, existing bond prices rise. This only affects investors who sell before maturity.
- Duration measures interest rate sensitivity — a bond with a duration of 10 loses approximately 10% of its market value for every 1 percentage point rise in rates, according to FINRA.
- Credit ratings from Moody’s, S&P, and Fitch classify bonds as investment grade (BBB-/Baa3 or higher) or high yield (below that threshold) — the dividing line between institutional-quality and speculative debt.
- Bonds can be purchased directly, on the secondary market, or through bond mutual funds and ETFs — the latter providing the most accessible route to diversified fixed income exposure for most individual investors.
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