Latest / Monetary Policy Explained with Fexingo: Central Banks, Money Supply, and Interest Rates / How the Fed Actually Sets Interest Rates
Transcript
- Lucas: So the Federal Reserve says it's setting interest rates — and the headline number everyone watches is the federal funds rate. But how does the Fed actually get banks to pay that rate? It's not a magic wand. Luna: Right, there's a whole toolkit behind that number. And I think a lot of people assume the Fed just sends out a memo and everyone complies. Lucas: Exactly. And the answer is actually pretty mechanical. The Fed has two main tools to steer the federal funds rate: interest on reserve balances, or IOER, and the overnight reverse repurchase agreement facility — ON RRP for short. Luna: Let's start with IOER. That's the rate the Fed pays banks on the reserves they hold at the central bank, right? Lucas: Yes. So if the Fed wants to raise the federal funds rate, it raises IOER. Banks, being profit-maximizing, won't lend reserves to each other in the fed funds market at a rate lower than what they can get risk-free from the Fed. So IOER acts as a floor. Luna: But it's not a perfect floor, because not every institution that lends in the fed funds market is a bank. Money market funds and government-sponsored enterprises like Fannie Mae — they don't earn IOER. Lucas: That's exactly where ON RRP comes in. The Fed offers those non-bank lenders an overnight reverse repo facility where they can lend cash to the Fed at a rate slightly below IOER. That creates a soft floor for the entire market. Luna: So the Fed effectively sets a target range: the bottom is the ON RRP rate, and the top is IOER. And the federal funds rate lives somewhere in between. Lucas: Right. As of May 2026, that range is 4.00 percent at the bottom and 4.25 percent at the top. The actual effective federal funds rate has been hovering right around 4.08 percent — bang in the middle. So the system is working the way it's supposed to. Luna: But it wasn't always that tidy. I remember in September 2019, the federal funds rate spiked way above the target range. What happened there? Lucas: That was a classic reserve scarcity event. Back then, the Fed was still shrinking its balance sheet after the quantitative easing years. Corporate tax payments and Treasury settlement happened on the same day, draining a huge chunk of reserves from the banking system. Banks suddenly didn't have enough reserves to meet their settlement needs, so they bid aggressively for overnight funds, and the fed funds rate shot up to almost 10 percent. Luna: Ten percent. That's not a gentle nudge; that's a crisis. Lucas: It was a crisis. The Fed had to intervene with emergency repo operations to pump liquidity back in. And that experience led to the creation of a standing repo facility — a permanent backstop where banks can borrow reserves from the Fed at a penalty rate if the market rate gets too high. Luna: So the Fed learned that relying on just IOER and ON RRP wasn't enough when reserves got too low. They needed a ceiling too. Lucas: Exactly. Now they have a full corridor: the ON RRP rate is the floor, IOER is the middle, and the standing repo rate is the ceiling. So the fed funds rate stays contained. Luna: That's the short end. But what about long-term rates? The ten-year Treasury yield is way above the fed funds rate right now — it's around 4.7 percent, I think. Lucas: Yeah, the ten-year is at 4.7 percent, so you've got a term premium of about 60 basis points over the fed funds rate. The Fed doesn't directly control that. Long-term rates are driven by inflation expectations, growth outlook, and the term premium — which is compensation for uncertainty about future rates and inflation. Luna: So when people say the Fed 'sets rates,' they really only set very short-term rates. The rest of the yield curve is a market vote. Lucas: Precisely. And that's why the Fed's communication is so important. When the Fed signals that it will keep rates high for longer, that pushes up long-term yields because markets expect the short rate to stay elevated. That's the expectations channel. Luna: But there's a flip side: if the Fed loses control of the short end again — say reserves become scarce again — then the whole corridor breaks down. Lucas: That's the big risk. The Fed has been shrinking its balance sheet again through quantitative tightening. As of May 2026, reserves have fallen to about $3.2 trillion. That's still well above the level in 2019 when things broke, but if Treasury general account balances spike or if there's a sudden demand for cash, we could see similar stress. Luna: And the Fed has said it will stop QT if reserves approach 'ample' levels. But defining 'ample' is a judgment call. Lucas: It is. And that's why the standing repo facility is such a crucial backstop. It means the Fed can tolerate lower reserves without losing control of the fed funds rate, because if the rate tries to spike, banks can borrow from the standing repo facility and push it back down. Luna: So the lesson is: the Fed has a lot more tools than people think. It's not just a single rate cut or hike. There's a whole plumbing system underneath. Lucas: And understanding that plumbing helps you make sense of why, for example, the Fed sometimes shifts its target range by a quarter point, but the effective fed funds rate barely moves — because the corridor already had it contained. Luna: Or why a sudden spike in repo rates in 2019 had nothing to do with the economic outlook and everything to do with a technical shortage of reserves. Lucas: Right. So next time you hear 'the Fed raised rates by 25 basis points,' you can picture that corridor shifting up: ON RRP goes up, IOER goes up, the standing repo rate goes up. And the market finds its new equilibrium inside that range. Luna: It's almost like a thermostat: the Fed sets the upper and lower bounds, and market forces determine the exact temperature inside. Lucas: I like that analogy. And like a thermostat, if the system loses power — or if reserves get too low — the temperature can swing wildly. That's why the Fed has built all these safety valves. Luna: Alright, so for someone listening who has a mortgage or a credit card, how does this actual plumbing affect them? The fed funds rate is a wholesale rate, not a consumer rate. Lucas: It filters through. Most variable-rate consumer debt — credit cards, home equity lines of credit — is tied to the prime rate, which moves in lockstep with the fed funds rate. So when the Fed shifts its target range, your credit card APR moves within a billing cycle or two. Luna: And mortgages? Fixed-rate mortgages are tied more to the ten-year Treasury, which as we said is driven by expectations and term premium. Lucas: Right. So the Fed's action on the short end influences the long end, but it's indirect. If the Fed signals it will cut rates next year, the ten-year yield might drop because inflation expectations fall. But if the Fed also says it's worried about fiscal deficits, the term premium could push long rates higher. It's a tug of war. Luna: So the real takeaway is: the Fed's control is strongest at the very short end, weaker as you go out the curve. But because all rates are connected, their actions still ripple across the whole economy. Lucas: Exactly. And the more you understand the mechanics — the IOER, the ON RRP, the standing repo facility — the less mysterious it seems. It's not magic. It's plumbing. But it's plumbing that affects whether you can afford a house or a car. Luna: So with the fed funds rate at 4.00 to 4.25 percent in May 2026, and the ten-year at 4.7 percent, what's your take? Is the Fed in control, or is there a risk they lose the short end again? Lucas: I think they're in control for now. Reserves are still ample enough, and the standing repo facility gives them a credible ceiling. But if QT continues for another year and reserves drop below $3 trillion, we might start seeing more frequent bouts of volatility in overnight markets. The Fed will have to decide whether to stop QT or expand the standing repo facility further. Luna: So it's a balancing act. Too much tightening and the plumbing breaks. Too little and inflation might reignite. Lucas: That's the central banker's dilemma in 2026. And it's why, even though the tools are mechanical, the decisions are deeply judgment-based. Luna: Thanks, Lucas. I think a lot of listeners will never look at a Fed rate decision the same way again. Lucas: I hope so. The more people understand the actual machinery, the less intimidating monetary policy becomes. And that's good for everyone.