Latest / Monetary Policy Explained with Fexingo: Central Banks, Money Supply, and Interest Rates / How Central Banks Manage the Trilemma of Exchange Rates
Transcript
- Lucas: So let me start with a question that might sound almost philosophical. Can a central bank control its own interest rates, keep its currency pegged to another, and let money flow freely across its borders — all at the same time? Luna: I'm guessing the answer is no, because that sounds like having your cake and eating it too. Lucas: Exactly. And that's the core of what economists call the 'impossible trinity,' or the trilemma. It says you can only pick two out of three: a fixed exchange rate, free capital movement, and an independent monetary policy. Every central bank has to choose which two matter most, and which one they're willing to sacrifice. Luna: I remember studying the Mundell-Fleming model in school, but it always felt abstract. Can you give me a real-world case where this trade-off played out? Lucas: Arguably the most dramatic example in modern times is the Swiss National Bank in January 2015. For years, the SNB had pegged the Swiss franc to the euro at 1.20 francs per euro. They did it because the franc kept strengthening during the eurozone debt crisis, and that was crushing Swiss exporters. Luna: Right, because a stronger currency makes your exports more expensive abroad. Lucas: Exactly. So the SNB chose to fix the exchange rate — that was one corner of the trilemma. They also allowed free capital movement, because Switzerland is a global financial hub. That meant the third corner — independent monetary policy — was the one under pressure. Luna: How so? They still set interest rates, didn't they? Lucas: They did, but they had to subordinate those rates to defending the peg. If the European Central Bank eased policy, the SNB had to ease too — or else the franc would appreciate. So they were effectively importing the ECB's monetary policy. They kept rates at zero or negative, and they printed francs to buy euros to maintain the peg. Luna: That sounds unsustainable. Something had to give. Lucas: And it did. On January 15, 2015, the SNB suddenly abandoned the peg. No warning. The franc surged 30 percent against the euro in minutes. The Swiss stock market crashed. Exporters like Swatch reported massive losses. And the SNB's balance sheet took a hit because they were holding billions in euros that had just lost value. Luna: So they went from 'we control the exchange rate' to 'we have independent monetary policy but we just crushed our exporters.' That's the trilemma in action. Lucas: Exactly. They swapped the fixed exchange rate for monetary independence. They could finally set rates for Switzerland's needs, not for Europe's. But they lost the stability that the peg provided. And that decision has shaped Swiss policy ever since. Luna: Are there countries that have successfully managed all three corners for a long time? Lucas: Not really. Some try to fudge it. China, for example, has a managed float with capital controls. That allows them some monetary independence while keeping the renminbi relatively stable. But those controls create inefficiencies and black markets. Luna: And the Eurozone? They've got a fixed exchange rate within the single currency, free capital movement, but no independent monetary policy for individual member states. Lucas: That's the classic case. Each member country gave up its own central bank and interest rate setting. They outsourced that to the ECB. So they have two corners — fixed exchange rates and free capital — but lose the third. Luna: So when Greece needed different interest rates than Germany during the debt crisis, they couldn't have them. That's the trilemma biting. Lucas: Exactly. And that's why some economists argue that the euro is inherently unstable without fiscal union. But that's a bigger conversation. The key insight is that the trilemma forces hard choices. Luna: Let's go back to the SNB. How did they defend the peg for nearly three and a half years before giving up? Lucas: They bought euros aggressively. In 2014 alone, their foreign currency reserves more than doubled to over 400 billion francs. They also lowered interest rates to negative territory, which made holding francs less attractive. But the pressure kept building as the euro weakened. Luna: And then the ECB announced quantitative easing in January 2015. That must have been the final straw. Lucas: Exactly. The ECB was about to print massive amounts of euros, which would have weakened the euro further. To maintain the peg, the SNB would have had to print even more francs and buy even more euros. They decided the cost — the inflation risk, the balance sheet risk — was too high. Luna: So they chose independent monetary policy over a fixed exchange rate. And the market reaction was brutal but short-lived. Lucas: Right. The franc quickly stabilized around 1.00 to 1.10 per euro, and the economy adjusted. Swiss exporters had to improve productivity or accept lower margins. Some didn't survive. But the trilemma says you can't have all three, so something had to break. Luna: Are there any modern examples of countries that have chosen differently? Lucas: Hong Kong is a fascinating case. They have a currency board that pegs the Hong Kong dollar to the U.S. dollar at 7.80. They also have free capital movement. That means they have zero independent monetary policy. Their interest rates follow the Fed's exactly, even when that's not good for Hong Kong's economy. Luna: And they've maintained that peg since 1983. That's over 40 years. Lucas: Because they are willing to sacrifice monetary independence. They have huge reserves, a transparent system, and strong credibility. But it also means that when the Fed raises rates, Hong Kong's property market can get squeezed even if the local economy is weak. Luna: So the trilemma is a useful framework for understanding why central banks make the choices they do. It's not just theory — it's a real constraint. Lucas: Absolutely. And if you find that kind of economic logic satisfying, I think you'd really enjoy the deeper dives we do on this show. We keep it ad-free and focused on the concepts that actually explain how the world works. Luna: Yeah, and if you get value from that, listeners can support the show at buy me a coffee dot com slash fexingo. It's a low-key way to help us keep going. Lucas: Exactly. No pressure, but every bit helps. Anyway, coming back to the trilemma — one thing I find interesting is how the framework is evolving in a world of digital currencies and capital controls. Luna: Are central banks looking at ways to break the trilemma? Or is it still a hard constraint? Lucas: Most economists think it's still a hard constraint. But some argue that with central bank digital currencies, you could have more granular capital controls — like limiting outflows but allowing inflows — which could soften the trade-off. Luna: That's a good topic for a future episode. For now, I think the takeaway is that every central bank faces this choice, and there's no magic bullet. Lucas: Right. And the best ones communicate clearly which two they've chosen, and why. Thanks for listening. Luna: Thanks, everyone.