Latest / Monetary Policy Explained with Fexingo: Central Banks, Money Supply, and Interest Rates / Why Central Banks Care About Your Bank's Capital Ratio
Transcript
- Lucas: So you know how every central bank meeting, everyone obsesses over the interest rate decision. But there's another number on that same table that arguably matters just as much for the real economy, and it gets almost no attention. It's the capital ratio of the banking system. Luna: The capital ratio. That's the thing where regulators say a bank has to hold a certain percentage of its assets as equity, right? Lucas: Exactly. But it's more than just a safety buffer. For central banks, it's become a lever. They can raise or lower the requirement to influence how much credit banks extend. And in the last decade, especially after 2023, that lever has been pulled a lot. Luna: Can you give me a concrete example of when that lever actually worked? Lucas: Sure. Look at the regional banking stress in March 2023. Silicon Valley Bank and Signature Bank failed essentially because they had too little capital relative to the duration risk they took on. After that, regulators everywhere started looking at capital ratios much more closely. But before that, in the good years, they were using countercyclical buffers to cool credit growth. Luna: Countercyclical buffers. That's the macroprudential tool that goes up when credit is frothy and down when things are tight, right? Lucas: Right. And it's a central bank tool, not just a bank regulator's. In the UK, the Bank of England changes its countercyclical capital buffer rate. In Europe, the ECB does the same. It's literally a percentage of risk-weighted assets that banks have to hold as extra capital. When they raise it, banks have less room to lend. When they cut it, banks can free up capital and lend more. Luna: So it's like a speed limit for the economy. And central banks can adjust that speed limit without touching interest rates. Lucas: Exactly. And that's the angle I want to dig into today. We often think of central banks as having two tools: interest rates and the balance sheet. But capital requirements are a third, and arguably a more targeted one. It's aimed directly at the banks that are originating the credit. Luna: And it doesn't have the blunt impact on consumer loans and mortgages that rate hikes do. Lucas: Right. So let's start with what the ratio actually is. The headline number is the CET1 ratio, which stands for Common Equity Tier 1. That's the highest quality capital, primarily common shares and retained earnings. And it's expressed as a percentage of risk-weighted assets. Risk-weighted means that a mortgage to a prime borrower weighs less than a speculative corporate loan, because it's less likely to default. Luna: So a bank with a ten percent CET1 ratio has equity equal to ten percent of its risk-weighted assets. That seems thin, but it's actually the norm. Lucas: It is. And the minimum is typically around four and a half percent under Basel III, but the practical requirement is usually much higher. In Europe, banks run well above twelve percent. In the US, too. The point is that the buffer is what absorbs losses before depositors or taxpayers do. Luna: And that's why central banks care. If banks are well capitalized, they can keep lending through a downturn, which helps the economy recover. If they're undercapitalized, they pull back, and the central bank's rate cuts don't transmit as well. Lucas: That's the transmission mechanism. But there's a tension. When a central bank raises capital requirements, it's making banks safer, but it might also constrain lending. So there's a trade-off between stability and growth. And central banks have been getting more sophisticated at managing that trade-off. Luna: Can you give us an example of a central bank actually using the countercyclical buffer in real time? I remember the Bank of England talked about it during the pandemic. Lucas: Yeah, in March 2020, the Bank of England cut its countercyclical capital buffer from one percent to zero. That freed up an estimated one hundred ninety billion pounds for banks to lend. It was a direct attempt to keep credit flowing during the initial shock. And that move was coordinated with the rate cut and the bond-buying program. It was a one-two-three punch. Luna: And it worked? I mean, did it actually increase lending, or did banks just hoard the capital? Lucas: Studies suggest that it did support lending, but not uniformly. Banks that had stronger capital positions before the cut were more likely to use the relief to lend. Weaker banks used it to shore up their own balance sheets. So the tool is effective, but it's not a silver bullet. Luna: That makes sense. And it ties into the stress tests that central banks run. They don't just set ratios; they also test banks against hypothetical scenarios to see if they'd stay above the minimums. Lucas: Right. The Federal Reserve runs the Comprehensive Capital Analysis and Review, or CCAR, every year. And in 2025, they included a scenario with a severe recession, unemployment peaking at ten percent, and a fifty percent drop in commercial real estate prices. The results showed that the largest banks would stay well above minimum capital levels even under that stress. That's a signal to the market that the system is resilient. Luna: But some critics say that those stress tests are too lenient, or that they give banks a false sense of security. What's your take? Lucas: There's always a calibration debate. The models can't capture every tail risk. But the fact that stress tests have become a routine part of macroprudential policy is a shift. It's not just about the ratio today; it's about the ratio under a hurricane scenario. That's what makes a bank's capital planning credible. Lucas: And here's where it gets really interesting for central banks. They can use capital requirements to lean against the wind. If credit is growing too fast and household debt is piling up, they can raise the buffer. That's what the Bank of Korea did in 2021 when household borrowing surged. They raised the countercyclical buffer to cool the market. Luna: So it's a direct tool to address financial stability risks, not just inflation. And that's something that rate hikes alone can't do. Lucas: Exactly. In fact, that's why it's called macroprudential. It's about the stability of the whole system, not just the price level. And central banks have become increasingly comfortable using it. The ECB has a whole framework for setting the countercyclical buffer based on the credit to gdp gap. If that gap is widening, the buffer goes up. Luna: That sounds like a rule-based approach, but I imagine there's still a lot of judgment involved. Lucas: Oh, definitely. The credit to gdp gap is a starting point, but it's not a mechanical trigger. Central banks look at a range of indicators: property prices, lending standards, bank profitability. They have to make a call. And that's where the real art of central banking comes in. Luna: It also seems like there's a coordination aspect. If the Fed raises capital requirements while the ECB is cutting theirs, what happens? Banks might shift their lending across borders. Lucas: That's a real concern. And that's why the Basel Committee sets global standards. But there's still national discretion. And in a crisis, you saw coordination, like in 2020 when many countries cut buffers simultaneously. But in normal times, there can be divergence. That's part of the complexity. Lucas: So let's bring this back to the current moment, August 2026. We're coming out of a period where central banks hiked rates aggressively. Now they're starting to cut, but they're also signaling that capital ratios will remain a key tool. The Fed has said it plans to finalize the Basel III endgame rules, which would raise capital requirements for the largest banks. That's a big deal. Luna: Right, that's been a contentious issue. Banks argue that higher capital requirements will reduce lending and hurt the economy. Regulators argue that it's a necessary buffer against the next crisis. Lucas: And that's the crux. There's a genuine trade-off. But central banks are increasingly viewing capital as a first line of defense, not just a last resort. And that's a big shift from the pre-2008 mindset, where liquidity was the focus. Luna: So should the average person care about their bank's capital ratio? I mean, it's not like they check it before opening a checking account. Lucas: You should care indirectly. If your bank is well capitalized, it's more likely to survive a downturn, which means your deposits are safer, and it can keep lending to businesses in your community. And if the system is stable, the central bank doesn't have to do emergency bailouts, which protects taxpayers. So it's a hidden but critical piece of the economic infrastructure. Luna: And if today's episode gave you a clearer picture of how that infrastructure works, that's exactly why we do this show. We keep it ad-free, and the only way that stays possible is listener support. If you got something out of this, you can keep that going by buying us a coffee at buy me a coffee dot com slash fexingo. Lucas: Yeah, it really does help. And it also helps us know that we're on the right track. So if you've ever learned something from this show, consider chipping in. It goes right back into research and keeping things independent. Luna: And with that, let's get back to the capital ratio. One thing I want to dig into is how central banks actually judge whether a bank's capital is 'enough.' There's a difference between the minimum requirement and what's considered prudent. Can you walk us through that? Lucas: Sure. So there's the minimum, which is set by Basel III. But then there are buffers on top: the capital conservation buffer, the countercyclical buffer, and for global systemically important banks, an extra surcharge. So a typical large bank might have a total requirement of around eleven to twelve percent CET1, even though the bare minimum is four and a half. Luna: And if a bank dips below the buffer zones, what happens? Does the central bank force them to raise capital immediately? Lucas: No, and that's a key nuance. If a bank falls into the buffer, it faces restrictions on payouts, like dividends and share buybacks. That's to keep capital inside the bank. It's a gradual pressure, not a cliff. That was actually a lesson from the pandemic, where regulators wanted banks to use their buffers to absorb losses, not to hoard them. Luna: So it's a bit like a warning system that says 'slow down, rebuild your cushion.' Not 'stop everything and raise money now.' Lucas: Exactly. And that's why central banks can use these buffers as a countercyclical tool. When the cycle turns, they can tell banks, 'You can dip into this buffer to keep lending.' And that's a powerful way to support the economy without having to go through the legislature or the treasury. Luna: I think one of the big takeaways from today is that central banks have quietly added a third pillar to their toolkit. It's not just rates and balance sheet anymore. Capital ratios are now a front-line tool for steering the economy. Lucas: Yeah, and if you remember one thing, it's that the capital ratio is the speed limit on credit. Central banks can adjust that limit in real time, and it has a direct impact on how much money moves through the system. And that's a powerful thing to understand as you watch the next round of decisions from the Fed or the ECB. Luna: And next time you see a headline about a bank stress test, you'll know what it actually means. Lucas: Exactly. That's all for today. Thanks for listening, and we'll see you next time.