Interest Rate
Key Takeaways
- An interest rate is the cost of borrowing money, expressed as a percentage of the principal
- The Federal Reserve sets the federal funds rate, which influences all other rates
- Rising rates generally hurt stock and bond valuations; falling rates boost them
- Interest rates are the most powerful tool central banks have to manage the economy
Definition
An interest rate is the percentage charged by a lender to a borrower for the use of money, typically expressed as an annual percentage. Interest rates represent the cost of borrowing and the reward for saving. They are one of the most important variables in the financial system, influencing everything from mortgage costs to stock valuations.
The Federal Reserve sets the federal funds rate — the rate at which banks lend to each other overnight. This benchmark rate influences all other interest rates in the economy, including mortgage rates, savings account yields, corporate bond rates, and credit card rates.
Interest rates are determined by the supply and demand for money, inflation expectations, economic growth, central bank policy, and credit risk. When central banks raise rates, borrowing becomes more expensive, cooling economic activity and inflation. When they cut rates, borrowing becomes cheaper, stimulating growth.
How It Works
The Federal Reserve adjusts the federal funds rate target through its Federal Open Market Committee (FOMC) meetings, held eight times per year. Rate decisions are based on inflation data, employment figures, economic growth, and financial conditions. The Fed's dual mandate is to promote maximum employment and stable prices.
Interest rate changes ripple through the financial system. Higher rates increase mortgage costs (reducing housing demand), increase bond yields (reducing existing bond prices), increase the discount rate for stock valuations (reducing stock prices), and strengthen the currency (as foreign capital seeks higher yields).
The relationship between interest rates and bond prices is inverse: when rates rise, bond prices fall, and vice versa. The longer the bond's maturity, the more sensitive it is to rate changes. This interest rate risk is a primary consideration for bond investors and is measured by duration.
Example
When the Federal Reserve raised rates from 0.25% to 5.50% during 2022-2023, the effects were widespread. A 30-year mortgage rate rose from 3% to over 7%, increasing monthly payments on a $400,000 mortgage from $1,686 to $2,661 — a 58% increase. The S&P 500 fell 19% in 2022. Long-term Treasury bonds lost over 30% in value. Savings account yields rose from near 0% to 4-5%, finally offering meaningful returns to savers. The rate hiking cycle demonstrated interest rates' enormous influence on every corner of finance.
Why It Matters
Interest rates are arguably the single most important variable in financial markets. They determine the cost of capital for businesses, the attractiveness of different asset classes, the valuation of stocks and bonds, and the affordability of housing. The direction and level of interest rates should be a primary consideration in any investment strategy.
Understanding interest rates helps investors make better decisions about asset allocation. In rising rate environments, shorter-duration bonds, floating-rate instruments, and financial stocks tend to outperform. In falling rate environments, long-duration bonds, growth stocks, and real estate typically benefit.
Advantages
- Rising rates reward savers with higher yields on deposits and bonds
- Rate policy helps central banks manage inflation and economic growth
- Interest rates provide a mechanism for pricing risk in credit markets
- Rate differentials drive capital flows and currency valuations
Limitations
- Rate changes have lagged effects — impact takes 6-18 months to fully materialize
- Overly aggressive rate increases can trigger recessions
- Near-zero rates can create asset bubbles and excessive risk-taking
- Interest rate prediction is extremely difficult even for professionals
Frequently Asked Questions
Related Terms
Browse more definitions in the financial terms glossary.