Back to the Basics: Interest Rates Explained

The Fed adjusts interest rates based largely on inflation and the health of the economy

The Federal Reserve, or “the Fed,” is the central bank of the United States. Its primary goals are to promote maximum employment and stable prices, and its most powerful tool is the federal funds rate — the interest rate banks charge one another for overnight loans. While consumers don’t borrow at this rate directly, it influences borrowing costs across the economy, including mortgages, auto loans, credit cards, and business financing.

The Fed adjusts interest rates based largely on inflation and the health of the economy. When inflation is too high, it typically raises rates to slow spending and cool price pressures. When economic growth weakens or unemployment rises, it may lower rates to encourage borrowing, investment, and consumer spending. These decisions can have a significant impact on corporate earnings and stock valuations, particularly for growth stocks that are more sensitive to changes in interest rates.

Inflation reports, such as the Consumer Price Index (CPI) and Personal Consumption Expenditures (PCE) Price Index, are among the most closely watched economic releases because they heavily influence expectations for Fed policy. Higher-than-expected inflation can increase the likelihood of rates staying higher for longer, or even another rate hike, while cooler inflation often strengthens the case for future rate cuts.

Rather than waiting for the Fed’s decision, markets adjust these expectations in real time. For example, traders are currently pricing in a 61.9% probability that the Fed will keep its target rate at 3.50%-3.75%, compared to a 38.1% chance of a 25-basis-point rate hike.

Because financial markets are forward-looking, investors often react more to changes in interest rate expectations than to the Fed’s actual announcement. Every inflation report, jobs report, or Fed speech can shift expectations for future policy, causing stocks, bonds, and the U.S. dollar to move long before policymakers meet. Understanding how the Fed uses interest rates — and how markets interpret economic data — can help investors better understand the forces driving market volatility.