Every six weeks, twelve people gather in a conference room in Washington and decide what to do about a single number. That number is the federal funds rate — the interest rate at which US banks lend money to each other overnight. It sounds technical and obscure. It's the most important interest rate on the planet.
When they raise it, mortgages get more expensive everywhere from Phoenix to Paris. When they lower it, stock markets cheer and currencies move. The 12 people are the Federal Open Market Committee — the FOMC — and the number they set ripples through the entire global financial system within minutes of being announced. Here's how it actually works.
What it actually is
The federal funds rate is the interest rate at which US banks lend reserves to each other overnight. When one bank has too much money sitting at the Federal Reserve at the end of the day, and another bank has too little, they make a deal: the first bank lends the excess to the second, and charges interest. The interest rate they charge is the federal funds rate.
That sounds technical, and it is. But here's the key thing: the Fed doesn't directly set this rate. Instead, the FOMC sets a target range — typically a quarter-percentage-point band, like 4.25% to 4.50% — and then uses tools (open market operations, interest on reserves, the discount window) to keep the actual market rate within that band. The 'Fed funds rate' you see in headlines is the midpoint of the target range, or sometimes the actual effective rate the market is settling at.
So the real story isn't that the Fed picks a number and forces banks to use it. It's that the Fed manipulates the supply of reserves until banks are willing to trade at the target. The result looks the same, but the mechanism is more interesting than it first appears.
Why it controls everything else
If the Fed funds rate is just an overnight interbank rate, why does it matter for your mortgage, your credit card, your savings account, and your stock portfolio? Because of arbitrage.
Every other interest rate in the economy is, in some sense, a longer-duration bet on what the Fed funds rate will be in the future. The 3-month Treasury yield is essentially 'what's the Fed doing right now?' The 2-year Treasury is 'what does the market think the average Fed funds rate will be over the next two years?' The 10-year Treasury is the same question stretched over a decade. Mortgage rates layer on top of the 10-year. Corporate bond rates layer on top of the Treasury curve. Credit card rates layer on top of the prime rate, which is set by banks based on the Fed funds rate.
The whole structure is a stack, and the Fed funds rate is at the bottom of it. Move the bottom and everything above it shifts. This is why a single FOMC decision can move markets globally within seconds — the entire interest rate complex has to reprice to the new floor.
How rate decisions actually get made
The FOMC meets eight times per year, on a published schedule. The meetings last two days. Members include the seven Fed Governors (appointed by the President, confirmed by the Senate) and five of the twelve regional Federal Reserve Bank presidents (the New York Fed president always votes; the other four rotate).
At each meeting, they review economic data — inflation, employment, GDP growth, financial conditions — and decide what to do with the target range. Options are: hike (raise rates), cut (lower rates), or hold (leave them unchanged). The decision is announced at 2pm Eastern on the second day, along with a statement explaining the reasoning. Twenty minutes later, the Fed Chair holds a press conference where every word gets parsed by traders for hints about future moves.
The Fed has a 'dual mandate' set by Congress: maximum employment AND stable prices (typically interpreted as ~2% inflation). Most rate decisions are framed around the trade-off between these two. When inflation is too high, the Fed hikes (which slows the economy and brings inflation down, but risks unemployment). When unemployment is too high, the Fed cuts (which stimulates growth, but risks inflation). Threading this needle is what monetary policy is.
How to read it
For non-economists, the Fed funds rate matters in three practical ways:
- It sets the floor on cash returns. Your high-yield savings account, money market fund, and short-term CDs all pay roughly the Fed funds rate minus a small spread. When the Fed hikes, savings rates rise. When the Fed cuts, savings rates fall.
- It moves mortgage and loan rates indirectly. Mortgage rates technically track the 10-year Treasury, but the 10-year Treasury is itself influenced by current and expected future Fed funds rates. So Fed decisions reach mortgages with a small lag and some noise.
- It's the most important variable in stock valuations. Higher rates mean every other asset has to compete with cash for your money. When the Fed funds rate goes up, stocks have to deliver higher returns to be worth holding. This is why 'the Fed' is the single biggest factor in stock market direction over months-to-years horizons.
You can see the live 3-month Treasury yield (the cleanest market proxy for the current Fed funds rate) in the Bond Yield Explorer. It tracks Fed funds within 10-20 basis points and updates in real time during trading hours.