How Interest Rates Work: The Fed Funds Rate, Bonds & Your Portfolio
The Federal Funds Rate: Ground Zero
The federal funds rate is the overnight lending rate between banks. The FOMC sets a target range (e.g., 5.25%–5.50%), and the Fed uses open market operations and interest on reserve balances to keep the actual rate within that band.
This single rate cascades through the entire financial system. When the Fed raises it, banks pay more to borrow from each other, so they charge more on loans, offer higher deposit rates (eventually), and tighten lending standards. The ripple effect reaches every corner of the economy.
Types of Interest Rates
| Rate | What It Is | Set By | Typical Relationship to Fed Funds |
|---|---|---|---|
| Federal Funds Rate | Overnight interbank lending rate | Federal Reserve | The benchmark — everything else keys off this |
| Prime Rate | Rate banks charge their best customers | Banks (follows Fed) | Fed funds + 3% (moves in lockstep) |
| Treasury Bill Yield | Short-term government borrowing cost | Market (auctions) | Tracks fed funds closely |
| 10-Year Treasury Yield | Long-term government benchmark | Bond market | Influenced by Fed expectations + inflation + supply |
| Mortgage Rate (30-Year) | Home loan borrowing cost | Market | Roughly 10-Year Treasury + 1.5–2.5% spread |
| Corporate Bond Yields | Company borrowing costs | Market | Treasury yield + credit spread |
| SOFR | Secured overnight financing rate (replaced LIBOR) | Market | Tracks fed funds very closely |
Nominal vs Real Interest Rates
The nominal rate is what you see quoted. The real rate adjusts for inflation and tells you the actual return on lending or cost of borrowing. If a bond yields 5% and inflation is 3%, the real yield is about 2%. Real rates matter more than nominal rates for economic decisions — a 10% nominal rate with 8% inflation (2% real) is actually easier policy than a 4% rate with 1% inflation (3% real).
How Rate Changes Affect Asset Classes
| Asset Class | When Rates Rise | When Rates Fall |
|---|---|---|
| Bonds | Prices fall (inverse relationship). Longer duration = bigger hit | Prices rise. Long-duration bonds rally hardest |
| Growth Stocks | Underperform — future cash flows discounted more heavily | Outperform — lower discount rate boosts present value |
| Value Stocks | Often outperform (banks benefit from wider margins) | May underperform as growth stocks attract capital |
| Real Estate | Pressure on prices as mortgage costs rise | Supportive — cheaper financing boosts demand |
| Dollar | Strengthens (higher rates attract foreign capital) | Weakens (capital flows out seeking better yields) |
| Gold | Headwind (no yield, higher opportunity cost) | Tailwind (lower opportunity cost, weaker dollar) |
The Yield Curve and What It Tells You
The yield curve plots interest rates across different maturities. Normally, it slopes upward — longer maturities pay more to compensate for time and uncertainty. When it inverts (short-term rates exceed long-term rates), it signals the market expects future rate cuts, typically because a recession is approaching.
The steepness of the curve also matters. A steep curve (big gap between short and long rates) indicates expectations for strong growth and/or rising inflation. A flat curve signals uncertainty or expected slowdown.
Key Takeaways
- The federal funds rate is the anchor for all U.S. interest rates — every other rate keys off it.
- Real rates (nominal minus inflation) matter more than nominal rates for economic impact.
- Bond prices move inversely to rates; longer duration = more sensitivity.
- Rising rates generally hurt growth stocks, support the dollar, and pressure real estate.
- The yield curve shape reveals market expectations for growth, inflation, and future Fed policy.
Frequently Asked Questions
How does the Federal Reserve set interest rates?
The FOMC votes on a target range for the federal funds rate at eight meetings per year. The Fed then uses open market operations and the interest rate it pays on reserve balances to keep the actual overnight rate within that target range.
Why do interest rates affect stock prices?
Stocks are valued based on future cash flows discounted to present value. Higher rates increase the discount rate, reducing the present value of future earnings — especially for growth stocks whose earnings are further in the future. Lower rates do the opposite.
What is the relationship between interest rates and bond prices?
They move inversely. When rates rise, existing bonds with lower coupons become less attractive, so their prices drop. When rates fall, existing bonds with higher coupons become more valuable, so prices rise. Duration measures how sensitive a bond’s price is to rate changes.
How do interest rates affect the housing market?
Mortgage rates track the 10-year Treasury yield. When rates rise, monthly payments increase, reducing affordability and cooling demand. A 1% increase in mortgage rates can reduce purchasing power by roughly 10%, making housing the most rate-sensitive sector of the consumer economy.
What is the neutral interest rate?
The neutral rate (r*) is the theoretical rate that neither stimulates nor restricts the economy. If the Fed sets rates below neutral, policy is accommodative; above neutral, it’s restrictive. The neutral rate isn’t directly observable — the Fed estimates it around 2.5–3%, but this changes over time.