Fixed Income & Bonds

Direct Answer

Fixed-income investments are securities or pooled products whose value is tied primarily to debt obligations and contractual cash flows. Individual bonds can promise principal and interest payments subject to issuer terms and credit risk, while bond funds hold portfolios of debt securities and do not have one maturity date for the investor. Understanding yield, duration, credit quality, liquidity, taxes, and inflation is essential before comparing fixed-income products.

Swoopr already explains bond ETF mechanics, bond and fixed-income taxation, and macro and yield-curve concepts in depth. This page supplies the missing asset-class layer, explaining what a bond actually is and how to evaluate one, and sends you to those existing guides for specialist depth.

Key takeaways

• A bond is a debt claim, not an ownership claim like a stock.
• Bond prices and market yields generally move in opposite directions for a given fixed-coupon bond.
• "Yield" is not one number. Coupon rate, current yield, yield to maturity, and yield to worst answer different questions.
• Duration helps estimate price sensitivity to interest-rate changes; it is not simply "years until maturity."
• Credit risk can range from very low sovereign-credit exposure to speculative corporate debt with meaningful default risk.
• An individual bond and a bond fund can serve similar portfolio purposes but have different maturity, reinvestment, and price behavior.
• A high quoted yield can reflect higher risk rather than a free return advantage.

What is fixed income?

Fixed income covers debt securities and investment vehicles that primarily own debt. The issuer raises capital and promises payments according to the instrument's terms. Depending on the security, those terms can include periodic coupon payments, repayment of principal at maturity, inflation adjustments, floating rates, call provisions, or other features.

The category includes U.S. Treasury bills, notes, and bonds; Treasury Inflation-Protected Securities (TIPS); floating-rate Treasury notes; municipal bonds; corporate bonds; agency and mortgage-related debt; high-yield bonds; bond mutual funds and ETFs; and certain short-duration cash-management instruments.

These are not interchangeable. The source of repayment, maturity, tax treatment, credit quality, and embedded options can materially change risk.

If this is your entry point into the topic, start with bond basics, which works through the six contract terms that define any bond before price enters the picture.

Treasury marketable securities

The U.S. Treasury issues marketable bills, notes, bonds, TIPS, and floating-rate notes. TreasuryDirect states that investors can purchase marketable Treasury securities through TreasuryDirect using non-competitive bids or through banks, brokers, or dealers; the interest rate or yield for a new issue is determined through the auction process.

Treasury securities are backed by the U.S. government, but market-price risk still exists when a marketable security is sold before maturity. Government credit quality does not eliminate duration, inflation, or reinvestment risk. Treasury securities covers the published terms of each of the five marketable types, the single-price auction mechanism, and how TIPS handle both inflation and deflation.

Series I and EE savings bonds

Series I and Series EE bonds are non-marketable Treasury securities: they are registered to a single owner, cannot be bought or sold on a secondary market, and (since January 2025) are issued only in electronic form through TreasuryDirect. Both differ from the marketable Treasury bills, notes, and bonds described above in structure and purpose.

Both accrue interest for up to 30 years unless redeemed earlier, and interest compounds semiannually. TreasuryDirect, not a brokerage account, is the purchase channel for new issues of either bond. See Swoopr's existing Bond and Fixed-Income Taxation guide for how I bond and EE bond interest is taxed.

Series I and EE savings bonds works through the composite rate formula, what the 20-year doubling guarantee is actually worth as an annual return, and why redeeming an EE bond a month early forfeits all of it.

Bond cash flows

A plain fixed-rate bond can be understood through four components: face or par value, the amount generally repaid at maturity under the contract; coupon rate, the stated interest rate applied to par value; market price, what the bond trades for today; and maturity, the date principal becomes due, absent default or special provisions.

If a bond's coupon is more attractive than newly available comparable market rates, investors may bid its price above par. If its coupon is less attractive, its price may fall below par. This price adjustment is why yield and price are linked.

Coupon rate, current yield, and yield to maturity

Do not use "yield" without defining it.

Coupon rate is based on the bond's promised coupon and face value. It does not change merely because the bond's market price changes.

Current yield roughly compares annual coupon income with current market price. It ignores the gain or loss that can occur as a bond approaches maturity and generally ignores reinvestment assumptions.

Yield to maturity is an annualized return measure that incorporates the bond's current price, contractual cash flows, and repayment at maturity under specified assumptions, including no default and the reinvestment assumptions embedded in the calculation.

Yield to worst, for callable bonds, evaluates the least favorable yield among specified call or maturity scenarios. This matters because an issuer may have the right to redeem debt before final maturity.

Bond prices and yields works through all four measures side by side on one bond at three different prices, and shows how far yield to worst can sit below yield to maturity once a call feature is added.

Interest-rate risk and duration

When market yields rise, existing fixed-rate bonds generally become less valuable because new securities can offer more competitive yields. When yields fall, existing higher-coupon bonds can become more valuable.

Duration summarizes the sensitivity of a bond or bond portfolio to changes in yields. Modified duration can be used as a first-order approximation:

Approximate percentage price change ≈ −Modified Duration × Change in Yield

A bond with modified duration of 6 would have a first-order estimated price decline of roughly 6% for a one-percentage-point rise in yield, before accounting for convexity and assuming the yield change is appropriately modeled. This is an approximation, not a guaranteed price move.

Longer-maturity, lower-coupon bonds generally exhibit greater rate sensitivity than otherwise similar shorter-duration bonds. Swoopr's Bond Duration Explained guide separates Macaulay duration from modified duration and walks through the arithmetic on a real bond.

Convexity

Duration is a linear approximation. Bond price and yield relationships are curved. Convexity describes part of that curvature and helps refine estimates for larger yield changes. Advanced fixed-income analysis should use duration and convexity together rather than treating duration as exact.

Two security types have negative convexity, meaning they gain less when yields fall than they lose when yields rise. Callable bonds and yield to worst covers the version with a published redemption schedule, and mortgage-backed securities covers the version where thousands of borrowers hold the option and there is no schedule at all.

Credit risk and spreads

Credit risk is the possibility that an issuer cannot make promised payments. Investors often compare yields on non-Treasury debt with Treasury yields of similar maturity. The difference is commonly called a credit spread, although observed spreads can reflect more than pure default risk. Liquidity, embedded options, market technicals, and risk aversion can contribute too.

Important credit questions include how much debt the issuer carries, whether cash flow is sufficient to service interest and principal, what collateral or seniority applies, what covenants protect lenders, what refinancing needs are approaching, and how sensitive the issuer is to recession or falling commodity prices. A high yield can be compensation for a meaningful probability of loss.

Bond credit risk and ratings separates the two channels credit risk actually travels through, default and spread widening, and covers what seniority decides about recovery when a rating alone does not.

At the instrument level, corporate bonds covers the indenture, the covenant package and the capital structure that decide recovery, and high-yield bonds turns a spread into a break-even default rate you can test against published experience.

Credit rating agencies registered with the SEC (called nationally recognized statistical rating organizations) assign letter-grade opinions on an issuer's creditworthiness. Moody's uses Aaa down through Baa as its investment-grade tiers; S&P and Fitch use AAA down through BBB-. A rating of BBB- or higher (Baa3 or higher at Moody's) is investment grade; anything lower is speculative grade, commonly called high yield or junk. The SEC's Investor Bulletin on credit ratings cautions that a rating is not a guarantee of repayment, does not capture market or liquidity risk, and should not be treated as investment advice, partly because rating agencies are typically paid by the issuer they rate.

Municipal bonds

Municipal bonds are issued by states, local governments, and related entities. Tax treatment can differ from corporate debt, but "tax-exempt" should never be treated as a universal label: the tax consequences depend on the security and the investor's jurisdiction and circumstances. Swoopr's existing Bond and Fixed-Income Taxation guide owns the detailed tax explanation.

Municipal bonds covers the instrument itself: general obligation versus revenue pledges, how to use the MSRB's EMMA system for disclosure and trade prices, and how to convert a tax-exempt yield into a taxable equivalent at your own marginal rate.

Individual bonds versus bond funds

This distinction deserves attention because it is easy to assume the two behave identically.

SEC Investor.gov notes that bond funds can lose money and are exposed to credit, interest-rate, and other risks. "Bond fund" does not mean "cash substitute." Use Swoopr's existing Bond ETF Mechanics guide for ETF-specific trading, NAV, spread, and portfolio mechanics.

The trading row in that table is the one most often underestimated. Bond liquidity risk explains why the dealer market prices small orders worse than large ones, why the cost sits inside the price rather than on a commission line, and how to check reported trade data before buying an individual issue.

Bond ladders

A bond ladder divides capital among bonds that mature at staggered dates. The purpose is usually to distribute reinvestment dates and make future cash flows more predictable than placing all capital at one maturity.

A ladder does not eliminate credit risk, inflation risk, opportunity cost, reinvestment risk, or the liquidity constraints of selling bonds early. The design should be driven by liabilities and time horizon, not simply by picking a visually neat set of maturities.

Bond ladders works the structure through with numbers, compares it against a barbell and a bullet, and explains why callable rungs invert the whole design by disappearing together when rates fall.

Inflation and real return

Fixed nominal cash flows can lose purchasing power when inflation is high. Investors should distinguish nominal yield from expected real return. TIPS explicitly adjust principal based on the inflation index specified by Treasury, but their market prices still change, and their realized investment experience depends on purchase price, holding period, and taxes.

TIPS covers the adjustment mechanics, what the deflation floor does and does not protect, and the breakeven inflation rate that decides whether a TIPS or a conventional Treasury wins.

The yield curve and macro environment

The yield curve compares yields across maturities. Its shape can reflect market expectations, term premiums, monetary policy, and risk conditions. Avoid simplistic rules such as "an inverted curve guarantees recession" or "long rates equal future short rates."

Swoopr's existing Macro, Economics & Market Regimes hub remains canonical for yield-curve interpretation, monetary policy, and cross-asset macro analysis. This page links there to explain why those macro variables matter to bond investors.

How bonds are purchased

The purchase channel depends on the security. New-issue Treasury bills, notes, bonds, TIPS, and Series I and EE savings bonds can be bought directly from the U.S. government through TreasuryDirect, generally without a fee. Marketable Treasury securities, corporate bonds, and municipal bonds also trade through banks, brokers, and dealers, either at new issue or afterward on the secondary market. Bond mutual funds and bond ETFs are bought like other fund shares, through a brokerage or fund-provider account rather than security by security.

Secondary-market bond trading is generally less standardized and less transparent than exchange-traded stock or ETF trading; individual bonds, especially smaller municipal issues, can have wide bid-ask spreads and limited liquidity. Specific order-entry mechanics, fees, and minimums vary by brokerage or platform, so confirm the current terms with whichever venue is being used rather than assuming they match another platform.

Fixed-income due-diligence checklist

Before buying an individual bond or bond fund, understand:

• Issuer or portfolio holdings
• Maturity and duration
• Yield measure being quoted
• Credit quality and spread
• Call and prepayment provisions
• Liquidity
• Fund expense ratio, where applicable
• Index or active mandate
• Tax treatment
• Inflation sensitivity
• Role in the overall portfolio

Common mistakes

• Treating a high yield as a high expected return without examining credit or default risk.
• Confusing coupon rate with yield to maturity.
• Assuming Treasuries cannot decline in market value.
• Assuming an individual bond held to maturity behaves like a perpetual bond fund.
• Ignoring duration when reaching for a slightly higher yield.
• Ignoring call and prepayment risk.
• Calling municipal income universally tax-free.
• Comparing bond and equity yields as if they measure the same economic claim.

Where to go next

The guides below are this cluster's learning path, in reading order. Each one expands a section of this page into full depth.

• Bond Basics: the six contract terms that define any bond, where the return comes from, and how to research a specific issue.
• Bond Prices and Yields: why price and yield move inversely, how bonds are quoted, and what coupon rate, current yield, yield to maturity, and yield to worst each measure.
• Bond Duration Explained: Macaulay duration, modified duration, and convexity, with a full worked example.
• Bond Credit Risk and Ratings: how credit risk reaches you through default and through spread widening, what seniority decides, and what a rating leaves out.
• Treasury Securities: bills, notes, bonds, TIPS, and floating rate notes compared on terms, interest, and risk, plus how the auction sets the rate.
• Bond Price & Yield to Maturity Calculator: run the price and yield relationship on your own inputs.
• Treasury Bills, Notes, Bonds, TIPS and FRNs: choosing between the five Treasury types once you know what each one is.

Once the path above is covered, these guides go instrument by instrument and structure by structure:

• Corporate Bonds: indentures, seniority, covenants, credit spreads, and how company debt actually trades.
• Municipal Bonds: general obligation versus revenue pledges, EMMA disclosure, and taxable equivalent yield.
• High-Yield Bonds: break-even default arithmetic, recovery assumptions, and why position size decides the outcome.
• TIPS: the principal adjustment, the limits of the deflation floor, and how to read a breakeven inflation rate.
• Series I and EE Savings Bonds: the composite rate formula, the 20-year doubling guarantee, purchase limits, and tax deferral.
• Mortgage-Backed Securities: pass-throughs, prepayment and extension risk, CMO tranches, and asset-backed deals.
• Callable Bonds and Yield to Worst: call schedules, make-whole provisions, and why yield to maturity is the wrong number.
• Bond Ladders: rungs, spacing and rollover rules, with worked income numbers and the barbell and bullet alternatives.
• Bond Liquidity Risk: the dealer market, embedded transaction costs, and how to check a bond trades before buying it.

Related reading elsewhere on Swoopr Investment:

• Bond ETF Mechanics: existing Swoopr ETF guide.
• Macro, Economics & Market Regimes: yield curve, monetary policy, and rates.
• Bond and Fixed-Income Taxation: existing Swoopr tax guide.
• Portfolio Management: how fixed income functions within an allocation.

FAQ

References

• U.S. Treasury, TreasuryDirect: Buying a Treasury Marketable Security
• SEC Investor.gov: Bond Funds and Income Funds
• SEC Investor.gov: Bonds or Fixed Income Products
• U.S. Treasury, TreasuryDirect: Series I Savings Bonds
• U.S. Treasury, TreasuryDirect: Series EE Savings Bonds
• SEC Investor.gov: Updated Investor Bulletin, The ABCs of Credit Ratings