What is a Bond?

A bond is a loan you make to a government or company. In exchange for lending your money, the borrower promises to pay you periodic interest (the coupon) and return your principal at a specified future date (maturity).

When a government needs to fund spending or a corporation needs capital, they issue bonds to investors rather than going to a bank. Investors who buy these bonds become creditors — they are owed money, which makes bonds fundamentally different from stocks, where you are an owner.

A simple example: You buy a US Treasury bond with a face value of $1,000, a 4.5% coupon, and a 10-year maturity. Every year for 10 years, you receive $45 in interest. After 10 years, you receive your $1,000 back. Total return: $450 in interest plus your principal.

Bonds are the foundation of the global financial system. The US Treasury bond market — worth over $25 trillion — is the world's most important financial market, setting the benchmark interest rate for mortgages, corporate loans, and nearly every other financial product.

Key Bond Terms

Face Value (Par Value) The principal amount of the bond — what the issuer will repay at maturity. Most bonds have a face value of $1,000.

Coupon Rate The annual interest rate paid on the face value, expressed as a percentage. A $1,000 bond with a 5% coupon pays $50/year (usually in two semi-annual payments of $25).

Maturity The date on which the issuer repays the face value. Bonds are classified by maturity:

• Short-term: 1–3 years
• Medium-term (notes): 3–10 years
• Long-term: 10–30 years

Yield The actual return an investor earns based on the price paid and the coupon received. Yield changes as the market price of the bond changes — even though the coupon is fixed.

Duration A measure of a bond's sensitivity to interest rate changes, expressed in years. A bond with a duration of 7 will lose approximately 7% of its value if interest rates rise by 1%. Longer-duration bonds are more sensitive to rate changes.

Credit Rating An assessment of the issuer's ability to repay. Rating agencies (Moody's, S&P, Fitch) assign grades:

Spread The yield difference between a corporate bond and a comparable Treasury bond. A 200 basis point spread means the corporate bond yields 2% more than Treasuries — compensation for taking on credit risk.

Why Bond Prices and Yields Move Inversely

This is the most important — and most misunderstood — concept in fixed income. When bond prices go up, yields go down. When bond prices go down, yields go up. They always move in opposite directions.

Why? A concrete example:

You own a bond paying 4% on a $1,000 face value — $40/year. New bonds are now being issued at 6%.

• Nobody will pay $1,000 for your 4% bond when they can buy a new 6% bond for $1,000
• To sell your bond, you must discount the price — say to $750
• At $750, your fixed $40 annual payment now represents a 5.3% yield ($40 ÷ $750)
• The lower price has pushed the yield closer to current market rates

The reverse is also true: if new bonds are issued at 2%, your 4% bond becomes very attractive. Buyers will pay a premium — say $1,200 — pushing the yield down to 3.3%.

Think of it this way: the coupon payment is fixed in dollar terms. When the price you pay for that fixed payment falls, the percentage return (yield) rises. When the price rises, the yield falls.

Types of Bonds

US Treasury Bonds Issued by the US federal government. Backed by the full faith and credit of the US government — considered the world's risk-free benchmark. Three main types:

• T-Bills — maturities under 1 year, sold at discount to face value
• T-Notes — 2 to 10-year maturities, pay semi-annual coupons
• T-Bonds — 20 to 30-year maturities, pay semi-annual coupons

TIPS (Treasury Inflation-Protected Securities) Treasury bonds whose principal adjusts with inflation (CPI). If inflation rises, the principal increases — so do coupon payments. Provides guaranteed real (inflation-adjusted) returns. Essential for inflation hedging.

Corporate Bonds Issued by companies to fund operations, acquisitions, or capital expenditures. Pay higher yields than Treasuries to compensate for credit risk. Divided into:

• Investment-grade (BBB/Baa and above) — lower risk, lower yield
• High-yield / junk bonds (BB/Ba and below) — higher risk, higher yield; behave more like stocks in stress periods

Municipal Bonds (Munis) Issued by state and local governments. Interest is typically exempt from federal income tax (and often state tax for residents). Particularly attractive for high-income investors in high tax brackets.

The Yield Curve

The yield curve plots the yields of bonds with identical credit quality (usually US Treasuries) across different maturities — from 1 month to 30 years. It is one of the most important economic indicators in finance.

Normal (upward-sloping) yield curve: Long-term bonds yield more than short-term bonds. This is the natural state — investors demand extra compensation for locking up money for longer and accepting more uncertainty. Signals a healthy, growing economy.

Flat yield curve: Short-term and long-term yields are similar. Often a transitional state, indicating economic uncertainty.

Inverted yield curve: Short-term bonds yield more than long-term bonds. Signals that investors expect interest rates to fall in the future — typically because they expect economic weakness or recession. Historically the most reliable recession predictor.

Key spreads watched by investors:

• 2s10s spread — the difference between the 10-year and 2-year Treasury yields. The most widely followed spread.
• 3m10s spread — the Fed's preferred spread for recession analysis.

Yield Curve Inversion as Recession Predictor

The yield curve has inverted before every US recession since the 1950s, with only one false positive (1966). This track record makes it the most respected leading indicator in macroeconomics.

Why does inversion predict recession?

When short-term rates exceed long-term rates, banks face a fundamental problem: they borrow short (deposits, short-term funding) and lend long (mortgages, business loans). When the yield curve inverts, lending becomes unprofitable — banks tighten credit, businesses struggle to borrow, and economic activity slows.

Historical record of the 2s10s inversion:

Important caveats:

• The lag between inversion and recession ranges from 6 to 24 months — too long to be a short-term trading signal
• Not every inversion leads to a severe recession; depth and duration of the inversion matter
• Markets can continue rallying for 12+ months after initial inversion

The yield curve is a warning system, not a market timer. Investors who sell everything the moment the curve inverts typically miss significant additional gains before any eventual downturn.

How Bonds Fit in a Portfolio

Bonds serve three roles in a diversified investment portfolio:

1. Income generation Coupons provide predictable cash flows — particularly valuable for retirees who need regular income without selling assets.

2. Capital preservation High-quality bonds (Treasuries, investment-grade) preserve capital better than stocks in economic downturns. During the 2008 financial crisis, 10-year Treasuries gained ~25% while the S&P 500 fell ~38%.

3. Diversification and negative correlation In risk-off environments, investors often flee to the safety of government bonds — driving prices up as stocks fall. This negative correlation reduces portfolio volatility.

Allocation guidance by life stage:

Bond ETFs for portfolio construction:

• BND — Vanguard Total Bond Market (broad US investment-grade)
• AGG — iShares Core US Aggregate Bond
• TLT — iShares 20+ Year Treasury (long duration, high rate sensitivity)
• TIPS / SCHP — inflation-protected Treasuries
• HYG / JNK — high-yield corporate bonds (higher risk)

In a 60/40 portfolio (60% stocks / 40% bonds), the bond allocation's primary job is not to maximize return — it is to dampen volatility and provide dry powder to rebalance into stocks after market crashes.

Key Takeaways

• A bond is a loan to a government or company; in return you receive periodic coupon payments and your principal at maturity
• Bond prices and yields always move inversely — rising rates push bond prices down; falling rates push them up
• Duration measures interest rate sensitivity: a duration of 7 means roughly 7% price loss per 1% rate increase
• US Treasuries are the risk-free benchmark; corporate bonds pay higher yields to compensate for credit risk; munis offer tax advantages
• The yield curve plots bond yields across maturities — an inverted curve (short rates > long rates) has preceded every US recession since the 1950s
• Bonds serve as income, capital preservation, and portfolio diversification — particularly valuable during equity bear markets
• The standard 60/40 portfolio holds bonds primarily to reduce volatility, not to maximize returns