Fixed income financing is how governments and companies borrow money by issuing bonds: the borrower receives cash upfront and promises the lender a set schedule of interest payments plus the return of the original amount on a fixed date. The investor becomes a creditor, not an owner, and knows from day one exactly what they are owed and when. That certainty is what “fixed” refers to, and it is the feature that separates this form of financing from selling stock or taking a variable-rate loan.
The Three Terms That Define a Bond
Every bond is built on three numbers set at issuance. Once they are signed, they do not change.
The principal, also called par value or face value, is the amount the borrower will repay at the end. For most bonds, it is $1,000 per bond. The coupon rate is the annual interest rate the borrower pays on that principal. A 5% coupon on a $1,000 bond means $50 per year, usually paid in two $25 installments six months apart. The rate is locked in and does not move with the broader market. The maturity date is when the borrower must return the full par value. It can sit anywhere from 90 days to 30 years out.
Missing any of these payments, whether a coupon or the final principal, is a default. For the borrower, default can bring credit rating downgrades, bankruptcy, and the loss of future access to capital markets. For the investor, it can mean losing part or all of the money lent.
How It Differs From Selling Stock
A company that needs money has two basic choices: borrow or sell ownership. Fixed income is the borrowing side. Buying a bond makes you a creditor with a legal right to your interest and your principal back, but you get no vote and no share of profits beyond the coupon.
Selling stock is the ownership side. Shareholders can vote and may receive dividends if the board declares them, and they benefit if the share price rises. Nothing about that is guaranteed.
The gap between the two shows up most starkly in bankruptcy. Bondholders sit ahead of stockholders in the repayment line. Secured bondholders, whose bonds are backed by specific assets, get paid first. Unsecured bondholders come next. Equity holders are last, and they often receive nothing once debts are settled. That priority is the core trade-off of the asset class: less upside than stocks, a stronger legal claim on the borrower.
The Main Types of Bonds
Who issues the debt shapes almost everything about it, including how risky it is, what it pays, and how the interest is taxed.
U.S. Treasury Securities
The U.S. Treasury borrows to fund federal operations and its debt is considered among the safest in the world because it carries the full backing of the federal government. Treasury debt comes in three forms sorted by maturity:
- Treasury Bills mature in one year or less. They pay no periodic interest; you buy them at a discount and receive the full face value at maturity, and the difference is your return.1TreasuryDirect. Treasury Bills
- Treasury Notes are issued in 2, 3, 5, 7, and 10-year terms and pay interest every six months.2TreasuryDirect. About Treasury Marketable Securities
- Treasury Bonds are issued in 20 and 30-year terms and also pay semi-annual interest.3TreasuryDirect. Understanding Pricing and Interest Rates
Inflation-Protected Securities
Fixed coupons carry a hidden weakness: inflation can chew through their real value over time. The Treasury sells two instruments designed to counter that. Treasury Inflation-Protected Securities (TIPS) come in 5, 10, and 30-year terms; the principal adjusts with the Consumer Price Index for Urban Consumers, and because interest is calculated as a percentage of that adjusted principal, the payments rise and fall with inflation too.4TreasuryDirect. Treasury Inflation-Protected Securities (TIPS) Series I Savings Bonds work differently: they combine a fixed rate that never changes with an inflation rate that resets every six months.5TreasuryDirect. I Bonds Interest Rates
Municipal Bonds
States and local governments issue municipal bonds to fund infrastructure, schools, and public services. Interest is generally excluded from federal income tax, and in some cases from state and local taxes as well.6Municipal Securities Rulemaking Board. Municipal Bond Basics They come in two flavors. General obligation bonds are backed by the full taxing power of the issuing government. Revenue bonds are repaid only from the income of a specific project, such as a toll road or water system, and typically carry more risk because everything depends on that one revenue stream. Credit quality varies widely across issuers, so ratings matter here more than with federal debt.
Corporate Bonds
Companies borrow to fund factories, acquisitions, and general operations. The issuer’s creditworthiness sets both the risk and the coupon it has to offer. Moody’s, S&P, and Fitch each rate corporate debt on parallel scales. Bonds rated BBB- (or Baa3 on Moody’s scale) and above are investment grade, meaning a relatively low probability of default. Anything at BB+ (Ba1) or below is speculative, commonly called high-yield or junk. High-yield bonds pay larger coupons precisely because investors will not accept the same return on a shaky borrower that they would on a blue-chip one.7S&P Global Ratings. Understanding Credit Ratings
Zero-Coupon Bonds and STRIPS
Some bonds pay no periodic interest at all. Zero-coupon bonds are sold at a deep discount to face value, and the investor’s entire return is the difference between purchase price and the par value received at maturity. The Treasury facilitates this through STRIPS, a program that splits a standard Treasury note or bond into separate zero-coupon pieces: one for the principal payment and one for each individual interest payment. STRIPS are bought and sold through brokers and dealers, not directly through TreasuryDirect.8TreasuryDirect. STRIPS
Securitized Products
Securitization bundles individual loans into a single tradable security. Mortgage-Backed Securities pool home loans and pass borrower payments through to investors. Asset-Backed Securities do the same with auto loans or credit card receivables. These instruments carry prepayment risk: when homeowners refinance or car buyers pay off loans early, investors get principal back sooner than planned and then have to reinvest at whatever rate the market offers.
Primary Market, Secondary Market, and Why Prices Move
Every bond starts in the primary market with the initial sale from borrower to investor. The Treasury sells at public auction. Corporations usually hire investment banks to underwrite new offerings, meaning the bank buys the bonds from the issuer and resells them to investors, taking on the risk of placing them.
Once that first sale closes, the bond enters the secondary market. Unlike stocks, most bonds trade over-the-counter through dealer networks rather than on a centralized exchange. A dealer buys a bond from one investor using the firm’s own capital and later sells it to another buyer at a markup. That structure makes bond pricing less transparent than stock pricing; there is no single ticker showing a continuously updated price.
The Price-Yield Relationship
The most important dynamic in bond trading is the inverse relationship between price and prevailing interest rates. When new bonds come to market at higher rates, existing bonds with lower coupons become less attractive, and their market price drops until the effective yield matches what new bonds offer. When rates fall, existing bonds with higher coupons become more valuable and trade above par.
That is where the distinction between coupon rate and yield-to-maturity matters. The coupon rate is fixed at issuance; a 5% coupon on a $1,000 bond always pays $50 a year regardless of the bond’s market price. Yield-to-maturity (YTM) is the total annualized return an investor earns if they buy at the current market price and hold to maturity. Pay $950 for that same $1,000 bond with a 5% coupon and your YTM exceeds 5%, because you collect the $50 coupon each year plus a $50 gain when the full par value is repaid at the end.
What Can Go Wrong
Bonds are often called safe, and compared to stocks they usually are. Risk-free they are not. The risks work differently from equity risk, and knowing them is how you avoid surprises.
Interest Rate Risk and Duration
Rising interest rates push bond prices down. The longer a bond’s remaining maturity, the more its price will move when rates shift. A 30-year Treasury will lose far more market value from a 1% rate increase than a 2-year note will. Duration is the standard measure of that sensitivity: it expresses the approximate percentage change in a bond’s price for a 1% change in interest rates. A bond with a duration of 7 would drop roughly 7% in price if rates rose by one percentage point.9FINRA. Bonds, Interest Rate Changes, and Duration If you plan to hold to maturity, price swings along the way matter less; you still get par value at the end. If you might need to sell early, duration tells you how much market risk you are carrying.
Credit Risk
Credit risk is the chance the borrower cannot make its payments. Treasury securities carry virtually none because they are backed by the federal government. Investment-grade corporate bonds carry moderate risk. High-yield bonds carry substantial risk, which is the reason they pay higher coupons. Credit ratings are not static, either. When an agency downgrades an issuer, the market price of that issuer’s bonds falls immediately as investors demand a higher yield to hold weaker debt.
Call Risk and Reinvestment Risk
Many corporate and municipal bonds include a call provision letting the issuer buy the bonds back before maturity at a set price. Issuers usually exercise this when interest rates have fallen: they retire expensive debt and reissue at lower rates.10FINRA. Callable Bonds – Be Aware That Your Issuer May Come Calling For the investor, that creates reinvestment risk. You get your principal back early and have to redeploy it in a market where rates are worse than what your original bond was paying. Call risk is most acute with callable bonds precisely because calls happen when reinvestment options are least attractive.
How the Income Is Taxed
How your bond income is taxed depends on who issued the bond, and misjudging this can undercut the after-tax return you thought you were earning.
Interest from U.S. Treasury securities is subject to federal income tax but exempt from all state and local income taxes.11Internal Revenue Service. Topic No. 403, Interest Received In high-tax states, that exemption can make Treasuries more competitive than the stated yield suggests.
Municipal bond interest works the other way. It is generally exempt from federal income tax.6Municipal Securities Rulemaking Board. Municipal Bond Basics Buy bonds issued by your own state, and the interest is often exempt from state income tax as well. Out-of-state municipal bonds are typically taxable at the state level. That double exemption is why advisors often recommend in-state municipal issues to high-bracket investors.
Corporate bond interest is fully taxable at your ordinary federal income tax rate, plus any applicable state and local taxes. It is the least tax-efficient form of bond income, which is one reason corporate bonds need to offer higher pre-tax yields.
Zero-coupon bonds and STRIPS carry a complication of their own. Even though no cash arrives until maturity, the IRS treats the annual increase in the bond’s value as taxable income in the year it accrues, reported on a Form 1099-OID.8TreasuryDirect. STRIPS That phantom income is why zeros are usually best held in a tax-deferred account like an IRA.
Why a Borrower Would Choose Bonds Over Stock
From the issuer’s side, borrowing has real advantages over selling shares. The biggest is tax. Interest paid on debt is generally deductible as a business expense, which lowers the effective borrowing cost. A company in a 21% tax bracket paying 6% interest effectively borrows at roughly 4.7% after the deduction. Federal law caps the business interest deduction at 30% of adjusted taxable income in most cases, so heavily leveraged companies may not deduct all of their interest.12Office of the Law Revision Counsel. 26 USC 163 – Interest
Debt also leaves ownership alone. Selling new stock dilutes every existing shareholder’s stake and voting power. A bond issuance does not; bondholders have no say in how the company is run.
Governments do not have the option either way. They cannot sell shares of themselves, so debt is the only way to fund infrastructure, defense, and any spending that exceeds tax revenue. Treasury and municipal bonds are how governments bridge that gap.
Where Fixed Income Fits in a Portfolio
For investors, bonds play a different role than stocks. The job is capital preservation and steady income, not growth, which is why fixed income anchors most diversified portfolios. During stock sell-offs and recessions, high-quality government bonds tend to hold their value or appreciate as money moves toward safety. That tendency to move opposite to equities is what makes bonds an effective hedge; when the riskier part of the portfolio drops, the bond portion often cushions the fall. Pension funds and insurance companies hold large fixed income positions for exactly this reason. They need reasonable certainty they can meet future obligations.
Individual investors typically increase their bond allocation as they approach retirement, shifting from a growth-focused stock portfolio toward one built around predictable income and principal protection. A 60-year-old five years from retirement has far less ability to wait out a stock market downturn than a 30-year-old with decades ahead.
Individual Bonds vs. Bond Funds
Most retail investors reach fixed income through bond mutual funds or ETFs rather than by buying individual bonds. Funds offer instant diversification across dozens or hundreds of issuers, monthly income, and low minimums. Individual bonds take more capital to diversify properly; holding fewer than about 10 different issues concentrates risk in a way that undermines the stability bonds are supposed to provide.
The trade-off is control over maturity. Own an individual bond and you know exactly when principal comes back, assuming no default or early call. A bond fund has no maturity date; the manager continuously buys and sells, so net asset value fluctuates with interest rates and never settles at par. In a rising-rate stretch, fund investors can see their balance fall with no guarantee of recovering it by a specific date. For investors who plan to hold to maturity and want that certainty, individual bonds have the edge. For investors who prioritize convenience and diversification, funds are the practical choice.