Bonds Explained: How They Work and Why Your Portfolio Might Need Them

Bonds are the most misunderstood major asset class. Everyone agrees you're "supposed" to own some, nobody explains what they actually are, and most beginners treat them as magic safe money that just exists to balance out stocks. Here's what's actually going on, how bonds really behave, and whether you should own any.

What a Bond Actually Is

A bond is a loan. When you buy a bond, you're lending money to a government or a company, and they promise to pay you back — with interest — on a specific schedule.

That's it. That's the entire concept. A bond is an IOU with a defined interest rate and a defined repayment date.

The confusion comes from the jargon that surrounds bonds. Three words do almost all of the work:

Face value (or par value). The amount the bond will pay back at the end. If you buy a $1,000 face value bond, you get $1,000 at maturity.

Coupon rate. The annual interest rate, expressed as a percentage of face value. A $1,000 bond with a 5% coupon pays $50 per year in interest. (The name comes from when bonds were physical paper with coupons you'd clip off and mail in to get paid.)

Maturity. The date the bond matures and the issuer returns your face value. A 10-year bond matures 10 years after it's issued.

Example: You buy a 10-year US Treasury bond with a $1,000 face value and a 4% coupon. Every year for 10 years, the US government sends you $40. At the end of year 10, you get your $1,000 back. You made $400 in interest plus your original money. Done.

Why Bond Prices Fall When Interest Rates Rise

Here's the part that breaks everyone's brain. Bonds are supposed to be "safe," but in 2022 the US bond market had one of its worst years in history. The aggregate US bond index dropped about 13%. How can something "safe" lose that much money?

The answer is that bond prices move inversely to interest rates. When rates rise, existing bonds become less valuable (and therefore trade at lower prices). When rates fall, existing bonds become more valuable.

Here's why. Suppose you own a 10-year bond paying 3% interest. Then the Fed raises rates and brand-new 10-year bonds start paying 5%. Nobody wants your 3% bond at full price anymore — why would they, when they can buy a new one paying more? So your bond's price on the secondary market drops until its effective yield matches what new bonds offer.

This is mechanical. It's not a loss of credit quality — the government is still going to pay you back your face value at maturity. It's a mark-to-market price movement because of changing interest rate environments.

The longer the bond's maturity, the more sensitive it is to interest rate changes. A 30-year bond can swing 15–25% in a year if interest rates move meaningfully. A 2-year bond barely moves at all. This is captured in a metric called "duration," but the intuition is: longer maturity = bigger price swings.

Types of Bonds

Not all bonds are the same risk. The major categories:

Government bonds. Issued by national governments. US Treasuries are the most liquid bonds on earth and considered essentially default-free. Canadian government bonds are similar. These pay the lowest interest rates because the credit risk is near zero.

Investment-grade corporate bonds. Issued by large, financially stable companies — Apple, Microsoft, JPMorgan. Slightly higher yield than government bonds because there's some (small) chance the company could default. Still considered very safe.

High-yield (junk) bonds. Issued by companies with weaker credit. Much higher interest rates because the risk of default is real. In bad economic environments, junk bonds can lose 20%+ — they behave more like stocks than like "safe" bonds.

Municipal bonds (US only). Issued by states and cities. Interest is often tax-free at the federal level (and sometimes state level too), which makes them attractive to high-income investors in taxable accounts.

Inflation-protected bonds. US TIPS (Treasury Inflation-Protected Securities) and Canadian Real Return Bonds have their principal adjusted for inflation. In a high-inflation environment, they hold their purchasing power better than regular bonds.

Bond ETFs: The Easy Way to Own Bonds

Unless you have a very specific reason, individual investors should own bonds through bond ETFs rather than buying individual bonds. ETFs give you instant diversification across hundreds or thousands of bonds, continuous liquidity, and simple tax reporting.

The popular bond ETFs:

BND — Vanguard Total Bond Market ETF. Broad US investment-grade bonds. Expense ratio ~0.03%.

AGG — iShares Core US Aggregate Bond ETF. Similar to BND. Expense ratio ~0.03%.

VGIT — Vanguard Intermediate-Term Treasury ETF. Just US government bonds with moderate maturity. Lower risk than broad bond funds.

VAB (Canada) — Vanguard Canadian Aggregate Bond Index ETF. Canadian equivalent of BND.

XBB (Canada) — iShares Core Canadian Universe Bond Index ETF. Similar coverage.

For most beginners, picking one broad bond ETF and owning it is enough. Don't overthink the sub-categories unless you have a specific reason.

The Classic 60/40 Portfolio

For decades, financial advisors preached a "60/40 portfolio" — 60% stocks, 40% bonds. The idea was that bonds would smooth out the ride: when stocks crashed, bonds would hold steady or even rise, cushioning the overall portfolio.

This worked brilliantly for most of the 20th century. From 1982 to 2020, US bonds were in a multi-decade bull market as interest rates fell from 15% to near zero. The 60/40 portfolio produced equity-like returns with much less volatility.

Then 2022 happened. Stocks fell ~20%. Bonds also fell ~13%. For the first time in decades, the 60/40 didn't work — both sides dropped together. A lot of retirees who had 40% of their portfolio in bonds for safety got a brutal lesson in duration risk.

The 60/40 isn't dead — it recovered in 2023 and 2024 — but the experience was a reminder that "bonds always help when stocks fall" was never a law of nature. It was a tendency that can break in high-inflation environments where central banks raise rates sharply.

Do You Actually Need Bonds?

Here's the honest answer for a typical reader of this article:

If you're under 40 and decades from retirement: probably no. Your biggest risk isn't short-term volatility — it's not having enough money at retirement. Bonds reduce expected long-term return in exchange for lower short-term volatility, and you don't need that trade-off. 100% stocks, or something close to it, is fine.

If you're in your 40s or 50s: a small allocation can make sense. 10–30% in bonds provides some cushion without meaningfully dragging long-term returns. Think of it as psychological insurance — it reduces the odds that you'll panic-sell in a downturn.

If you're within 5–10 years of retirement: bonds become important. At this point, the "sequence of returns risk" matters. If stocks crash right before you retire, you don't have time to recover. Having 20–40% in bonds reduces how much you need to sell at depressed prices. This is when the 60/40 philosophy starts to earn its keep.

If you're retired: bonds are usually essential. You need income, stability, and protection against having to sell stocks at the worst possible time. 30–50% in bonds is typical for retirees, adjusted to personal circumstances.

One other use case: bonds as an emergency fund alternative. If you have 6+ months of expenses in cash and want marginally better returns without much more risk, short-term bond ETFs (like SGOV or BIL) can serve as a "not quite cash" holding. They pay a little more than high-yield savings and are extremely stable.

What About Just Putting Bond Money in a Target-Date Fund?

Target-date funds automatically shift you from stocks to bonds as you approach retirement. A Vanguard Target Retirement 2055 Fund starts nearly 100% stocks and gradually migrates to a more bond-heavy mix by 2055. You don't have to think about the bond question at all — the fund handles it for you.

For most people who don't want to actively manage allocation, this is honestly the simplest answer to "how much bonds should I own?" — you just buy the appropriate target-date fund and let the glide path do the work.

The Bottom Line

Bonds are loans with defined interest and defined maturity. Their price moves inversely to interest rates, and longer-maturity bonds move more. For most people, bond ETFs are the right way to own them. For most young investors, you don't actually need them yet. For people nearing or in retirement, they become increasingly important as protection against short-term market shocks.

The 60/40 portfolio isn't magic and can fail in unusual environments. But the underlying instinct — that a diversified portfolio should mix growth assets with stabilizing assets — is basically right for people whose time horizon has shortened.

If you're just starting out and building a portfolio, you probably don't need to worry about bonds yet. Revisit the question in your 40s. Fully engage with it in your 50s. And if you want to avoid thinking about it entirely, a target-date fund does the job automatically.