When most people hear "financial markets," they immediately think of the stock market. But here's a surprise: the bond market is actually larger than the stock market. At the end of 2023, outstanding U.S. bonds totaled over $54 trillion, while all U.S. common stock was worth roughly $38 trillion. Daily bond trading exceeds $910 billion.
Bonds are the backbone of corporate and government finance. When a company needs to build a factory, or when a city needs to construct a school, they don't issue stock — they borrow. Bonds are how that borrowing happens at scale. Some bonds are among the safest investments in the world; others are risky, high-yield instruments that can rival stocks for volatility.
A bond is simply a publicly traded loan. When you buy a bond, you're lending money to the issuer — a corporation, the federal government, or a municipality. In return, the issuer promises to pay you regular interest and eventually return your principal.
Every bond comes with an indenture agreement — a legal document spelling out exactly what the issuer owes and what happens if they can't pay. Think of it as the terms and conditions of a loan, but legally binding and publicly filed.
| Characteristic | What It Means | Typical Values |
|---|---|---|
| Par value | The principal amount the issuer promises to repay at maturity | $1,000 |
| Time to maturity | Years remaining until the principal is returned | 1 to 30 years |
| Coupon rate | Annual interest rate as a percentage of par value, usually paid semiannually | 2% to 10% |
| Call provision | Issuer's right to repay early, typically if rates have fallen | Often callable after 10 years |
| Bond price | Market price quoted as a percentage of par value | 80% to 120% of par |
Different entities issue bonds for different reasons, and each type carries its own risk profile:
Issued by the federal government to finance national operations. These are considered among the safest investments in the world — backed by the full faith and credit of the U.S. government. Because the risk is near zero, the yields are also the lowest.
Companies issue bonds to fund inventory, equipment, R&D, and expansion. The risk depends entirely on the company's financial health — Apple's bonds are far safer than a struggling retailer's. Corporate yields are always higher than Treasury yields of the same maturity, and the gap (called the spread) widens with risk.
States, cities, and counties issue "munis" to fund public projects — schools, roads, water systems. Their key advantage: interest is typically tax-free at the federal level, making them attractive to investors in high tax brackets.
Bond prices are quoted as a percentage of par value. A bond quoted at 103 is trading at $1,030 (103% of $1,000 par). A bond at 97 costs $970.
| Field | Meaning |
|---|---|
| Coupon rate | Annual interest rate paid to bondholders |
| Maturity | Date the principal is repaid |
| Bid | Price at which you can sell |
| Ask | Price at which you can buy |
| Change (CHG) | Price change over the trading day |
| Ask Yield | Annual return if bought at ask price and held to maturity |
Bond valuation is a direct application of the time value of money. A bond's price equals the present value of all its future cash flows, discounted at the prevailing market interest rate.
Every bond provides two types of cash flow:
Where P = bond price, C = coupon payment, i = market discount rate per period, n = number of periods, and F = face value.
Consider a 20-year bond with a 7% annual coupon (paid semiannually, so $35 every 6 months) and a par value of $1,000. If the market demands a 6% annual yield (3% per semiannual period):
Because the 7% coupon exceeds the 6% market rate, this bond trades at a premium — investors pay more than par to capture the above-market coupon.
Not all bonds pay interest. A zero-coupon bond makes no periodic payments — instead, it's sold at a deep discount and pays the full par value at maturity. Your return comes entirely from the price appreciation.
What's the price of a $1,000 par zero-coupon bond maturing in 20 years, priced to yield 6%? Using semiannual compounding (standard for U.S. bonds):
P = $1,000 / (1.03)^40 = $306.56You pay $306.56 today and receive $1,000 in 20 years. That $693.44 difference is your accumulated interest — effectively a 6% annual return compounded semiannually.
Here's the most important relationship in bond investing: market interest rates and bond prices move in opposite directions. When rates rise, existing bond prices fall. When rates fall, existing bond prices rise.
A bond's coupon is fixed at issuance. If new bonds are being issued at higher rates, your old bond with its lower coupon looks less attractive — so its price must drop to offer the same yield as new bonds. The reverse happens when rates fall.
"Yield" isn't a single number — bonds have several yield measures, each telling you something different:
The simplest measure: annual coupon payment divided by current price.
Current Yield = Annual Coupon / Bond PriceEasy to compute, but it only captures the income portion — it ignores the capital gain or loss you'll experience as the bond price moves toward par at maturity.
The most meaningful yield measure. YTM is the total annualized return you'll earn if you buy at today's price and hold until maturity. It includes both coupon income and the price appreciation/depreciation to par. Computing YTM requires finding the internal rate of return of the bond's cash flows — essentially trial and error or a financial calculator.
If a bond is callable, the issuer might repay it early. Yield to call measures the return if the bond is called at the earliest call date rather than held to maturity. When rates fall, issuers often call bonds to refinance cheaper — so yield to call can be more relevant than YTM for callable bonds.
Municipal bonds pay tax-free interest. To compare a muni yield to a taxable bond yield, adjust for taxes:
Taxable Equivalent Yield = Muni Yield / (1 − Tax Rate)A 4% muni yield for an investor in the 24% bracket equals a 5.26% taxable yield (4% / 0.76). Suddenly that "low" muni yield looks much more competitive.
Credit risk — the chance the issuer won't make payments — is the primary driver of yield differences between bonds. Rating agencies grade bonds by credit quality:
| Rating | Quality Level | What It Means |
|---|---|---|
| AAA | Highest quality | Extremely strong capacity to meet commitments |
| AA | High quality | Very strong capacity to meet commitments |
| A | Upper medium grade | Strong, but somewhat susceptible to economic downturns |
| BBB | Medium grade | Adequate protection, but vulnerable to adverse conditions |
| Rating | Level | What It Means |
|---|---|---|
| BB | Somewhat speculative | Major ongoing uncertainties |
| B | Speculative | Adverse conditions likely to impair capacity |
| CCC | Highly speculative | Currently vulnerable to nonpayment |
| D | Default | Payments are in default or jeopardized |
Beyond credit ratings, bonds differ in their collateral and priority:
In bankruptcy, senior bonds have priority claims over junior bonds. Senior bondholders get paid first from whatever assets remain. This priority structure means senior bonds carry lower yields — less risk, less reward.
Unlike stocks, which trade primarily on exchanges, bonds trade in a decentralized, over-the-counter (OTC) market. Most trades happen between bond dealers and large institutions — mutual funds, pension funds, and insurance companies. The NYSE operates the largest centralized U.S. bond market, but it's small compared to the OTC market.
Explore these to deepen your understanding of this chapter's topics:
▶ YouTube Valuation of Bonds and Yield to Maturity ▶ YouTube Yield to Maturity Explained in 5 Minutes ▶ YouTube YTM — Approximate YTM and Bond Pricing 📖 Investopedia Bonds — Definition, Types, and How They Work 💬 Reddit r/bonds — Fixed income discussions