Bonds Explained -

How Lending Money Generates Returns

Bonds are one of the most widely used investment instruments in the world. They work differently from stocks — and understanding that difference helps clarify when and why they might be appropriate in a portfolio.

What a Bond Is

When governments or companies need to raise money, they can borrow it from investors by issuing bonds. A bond is essentially a loan agreement — you provide the capital, and in return you receive regular interest payments over a defined period, plus the return of your original amount at the end of the term.

Unlike stocks, where returns depend on business performance, bonds have agreed terms set in advance. You know the interest rate, the payment schedule, and the repayment date before you invest.

How Bonds Work in Practice

Consider a bond with the following terms:

Principal:         100,000 THB
Annual interest:   3% per year (3,000 THB)
Term:              10 years

Each year you receive 3,000 THB in interest payments. At the end of the ten-year term, you receive your original 100,000 THB back — provided the issuer remains solvent throughout the period.

Total interest received over ten years: 30,000 THB
Total returned at maturity: 100,000 THB

This predictability is one of the main reasons bonds are used — particularly by investors who need stable, regular income or want to reduce overall portfolio volatility.

Who Issues Bonds

Governments issue bonds to fund public spending, infrastructure, and national debt. Government bonds from stable countries — such as US Treasury bonds or Thai government bonds — are generally considered lower risk because the probability of a government defaulting on its debt is relatively low.

Companies issue bonds to raise capital for business purposes. Corporate bonds typically offer higher interest rates than government bonds — reflecting the higher risk that a company may be unable to repay.

The higher the interest rate a bond offers, the higher the risk generally associated with it. This is a direct application of the risk-return relationship.

What Influences Bond Prices

If you hold a bond until its maturity date, price fluctuations during the term are less relevant — you receive the agreed interest and your principal back regardless.

However, if you need to sell a bond before maturity, the price you receive in the market will vary based on current interest rates.

When interest rates rise, existing bonds with lower fixed rates become less attractive — their market price falls. When interest rates fall, existing bonds with higher fixed rates become more valuable — their market price rises.

This relationship between interest rates and bond prices is one of the more counterintuitive aspects of bond investing — but it is important to understand if you plan to sell before maturity.

The Risks of Bonds

Bonds are generally considered lower risk than stocks — but they are not risk-free. The main risks include:

Default risk — if the issuer cannot repay the loan, investors may lose some or all of their investment. This risk is higher with corporate bonds than government bonds, and higher with lower-rated issuers.

Interest rate risk — rising interest rates reduce the market value of existing bonds. This matters if you plan to sell before maturity.

Inflation risk — if inflation exceeds the bond’s interest rate, the real purchasing power of the returns is negative. A bond paying 3% per year in an environment of 4% inflation is effectively losing value in real terms.

Bonds and Portfolio Construction

Bonds are rarely used in isolation. Their primary role in most portfolios is to provide stability and reduce overall volatility — particularly when stock markets experience significant declines.

A portfolio that holds both stocks and bonds will typically be less volatile than one that holds only stocks. The trade-off is that expected long-term returns may be lower, since bonds generally offer lower returns than stocks over time.

The appropriate balance between stocks and bonds depends on individual goals, time horizon, and tolerance for short-term fluctuations.

Key Takeaways

A bond is a loan — you lend money to a government or company and receive interest in return
Terms are agreed in advance — interest rate, payment schedule, and repayment date
Holding a bond to maturity returns your principal, provided the issuer remains solvent
Higher interest rates on a bond generally indicate higher risk
Key risks include default, interest rate movements, and inflation
Bonds are typically used to provide stability and reduce volatility in a diversified portfolio

Frequently Asked Questions

Are government bonds safe?
Government bonds from financially stable countries are among the lower-risk investments available — but they are not entirely risk-free. Inflation, interest rate changes, and in rare cases sovereign default can all affect returns.

What is a bond rating?
Credit rating agencies assess the financial strength of bond issuers and assign ratings — from high-grade (low risk) to speculative (high risk). These ratings provide a useful starting point for evaluating the risk associated with a specific bond.

Can individual investors buy bonds in Thailand?
Yes. Thai government bonds can be purchased through the Bank of Thailand’s savings bond programmes and through licensed brokers. Corporate bonds are available through regulated brokerage accounts. Minimum investment amounts vary by product.