Key Highlights

• A bond allows a government, bank or company to borrow money from investors for a defined period.

• Bond prices and yields generally move in opposite directions.

• Inflation, interest-rate expectations, borrower risk and Supply and Demand can influence bond yields.

• Bond markets can affect fixed Mortgage rates, Business borrowing, Superannuation and government budgets.

Bond markets often sit behind some of the biggest moves in interest rates, borrowing costs and Investment markets, yet the mechanics can appear complicated. At its simplest, a bond is a borrowing contract. An investor provides money to a government, bank or company, while the issuer agrees to make specified payments and repay the principal at maturity. Understanding how bond prices and yields interact helps explain why movements in government Debt markets can eventually reach households, businesses and investors.

How Does a Bond Work?

When an investor buys a newly issued bond, the investor is effectively lending money to the issuer. In return, the bond normally provides regular interest payments, known as coupons, and repayment of its Face Value at maturity. Unlike many ordinary loans, bonds can often be traded after issuance in a secondary market. This means the investor receiving the payments can change even though the issuer’s obligations remain.

Governments use bonds to finance expenditure, while companies and banks can use them to raise capital. The return demanded by investors depends partly on how long the money is being lent, the perceived creditworthiness of the borrower and conditions across financial markets.

Why Do Bond Prices and Yields Move in Opposite Directions?

A bond’s Market Price can change after it is issued. If newly issued bonds begin offering higher returns, an older bond paying a lower coupon becomes less attractive unless its market price falls. The lower purchase price increases the effective return available to a new buyer. Conversely, when market interest rates fall, an existing bond with a comparatively attractive coupon can become more valuable.

This inverse relationship is central to understanding bond markets: falling bond prices generally mean rising yields, while rising prices generally mean lower yields. The Yield therefore provides a way of comparing the return available from bonds trading at different prices.

What Moves Bond Yields?

Several forces can influence yields. Central-bank interest rates affect expectations for short-term borrowing costs. Inflation matters because investors may demand a higher return when the future purchasing power of money is expected to fall. Longer maturities can carry greater uncertainty, while borrowers considered riskier generally need to offer more attractive returns.

Supply also matters. Heavy government or corporate borrowing increases the amount of debt investors are being asked to absorb. If demand does not rise at the same pace, issuers may need to offer higher yields. Investors can also demand an additional return, known as a term premium, for holding long-dated debt when the economic or fiscal outlook is uncertain.

Why Bond Markets Matter Beyond Investors

Government bond yields are widely used as benchmarks for borrowing costs elsewhere in the economy. Variable mortgage rates in Australia are more directly linked to the RBA cash rate, while fixed mortgage pricing is more closely connected to market funding costs and bond yields. Higher yields can also increase financing costs for companies, potentially influencing investment, hiring and expansion decisions.

Bonds also feature in many superannuation portfolios, meaning people can have exposure even if they never buy a bond directly. For governments, higher yields can raise the interest cost attached to new borrowing, leaving a larger portion of future budgets devoted to debt servicing.

What to Watch Next

Key indicators include the RBA cash rate, inflation, government borrowing programs, long-term Australian Government Bond yields and movements in major overseas markets such as US Treasuries. Together, these can provide clues about how financial markets are pricing future growth, inflation and interest rates.