Central banks became the largest single creditor in most developed economies
When the pandemic forced governments to borrow at unprecedented scale in 2020, central banks became the silent architects of stability — purchasing $4.5 trillion in sovereign debt and, in doing so, becoming the dominant creditor across the developed world. The OECD's February 2021 report acknowledged the necessity of this intervention while illuminating its shadow: economies now rest on a foundation of cheap money that cannot hold its shape forever. Nations like Portugal, carrying debt at 135.1% of GDP, stand at the edge of a transition where the very support that saved them may, in withdrawing, test them anew. The question history now poses is not whether the rescue worked, but whether the rescued are ready for the moment the rescuer steps back.
- Central banks absorbed more than half of all new sovereign debt issued across OECD nations in 2020 — a $4.5 trillion intervention that no peacetime precedent had prepared markets for.
- The very success of this strategy created a structural dependency: governments borrowed freely because a guaranteed buyer existed, leaving them deeply exposed if that buyer retreats.
- Portugal's debt-to-GDP ratio of 135.1% places it third in the eurozone's most indebted nations, making it acutely vulnerable to any rise in financing costs as central bank accommodation fades.
- The EU's suspended fiscal rules offer temporary shelter, but their eventual return will force a continent-wide confrontation with debt levels the old framework was never designed to absorb.
- Debt managers like Portugal's Cristina Casalinho are already moving — extending bond maturities to lock in low rates while the window remains open, racing the clock before policy tightens.
When the pandemic struck in 2020, governments across the developed world borrowed at a scale without modern precedent. Central banks stepped in as buyers of last resort, purchasing $4.5 trillion in newly issued sovereign bonds — more than half of all new government debt issued by OECD nations that year. In Japan and Sweden, central banks came to hold roughly 45% of all outstanding government debt; across Europe and the United States, the figure exceeded 20%. They had become, as the OECD's February 2021 report put it, the single largest creditor in nearly every developed economy.
The strategy was deliberate and, in the short term, effective. With private investors hesitant, central banks flooded bond markets to keep borrowing costs low and ensure liquidity. Governments funded relief programs, healthcare systems, and economic support without triggering a financing crisis. The money flowed. The immediate danger passed.
But the OECD's warning cut through the relief: the solution carried a deferred cost. As economies recovered and inflation climbed, central banks would eventually need to withdraw. When they did, governments would face a harder world — deeply indebted, stripped of easy financing, and exposed to rising borrowing costs on debt that would need to be refinanced. The most indebted nations would feel it most.
Portugal illustrated the stakes clearly. Ending 2020 with public debt at 135.1% of GDP — third highest in the eurozone after Italy and Greece — the country had little margin for error. The OECD projected that debt levels across the developed world would remain elevated well into 2021, with the risk of further increases if the pandemic persisted.
The recommended path was careful but actionable: build cash reserves, and use the current low-rate environment to extend the maturity of outstanding debt — locking in cheap financing before the window closed. Portugal's debt management chief, Cristina Casalinho, had already signaled this was the course her country intended to follow.
Beneath the technical debate lay a larger European tension. The EU's Stability and Growth Pact had been suspended to allow pandemic borrowing, but that suspension could not last indefinitely. When the rules returned, Europe would face a reckoning — how to honor fiscal frameworks designed for a different era while managing debt levels those frameworks were never built to accommodate, and how to do so without choking the recovery they were meant to protect.
When the pandemic hit in 2020, governments across the developed world needed money fast. They issued bonds. They borrowed. They spent. And central banks, the lenders of last resort, stepped in to buy those bonds in quantities never seen before.
By the end of that year, the numbers told a stark story: central banks in OECD countries had purchased $4.5 trillion in newly issued sovereign debt. That was more than half of all the new government bonds these countries had sold. In Japan and Sweden, the central banks now held roughly 45 percent of all outstanding government debt. In most European nations and the United States, they owned more than 20 percent. They had become, in the language of the OECD's report released in February 2021, the single largest creditor in nearly every developed economy.
This was not an accident. It was a deliberate strategy, born of necessity. Governments needed to borrow enormous sums to fund pandemic relief, healthcare, and economic support. Private investors were nervous. So central banks flooded the market, buying bonds in the secondary market to keep borrowing costs low and ensure there would always be a buyer. It worked. The money flowed. The crisis was cushioned.
But the OECD's warning was clear: this solution carried a hidden cost. As economies recovered and inflation began to rise, central banks would eventually need to step back. They would buy fewer bonds. They would tighten policy. And when they did, governments would face a new problem: they were now deeply indebted, and the easy financing that had sustained them would disappear. Borrowing costs would rise. Refinancing maturing debt would become expensive. Countries that had borrowed heavily would be most vulnerable.
Portugal was a case in point. The country ended 2020 with public debt equal to 135.1 percent of its annual economic output—the third highest ratio in the eurozone, behind only Italy and Greece. The OECD's projections suggested that debt levels across the developed world would remain elevated through 2021 and beyond, though the pace of increase might slow. But that forecast came with a caveat: if the pandemic dragged on, if lockdowns continued, debt would climb faster.
The organization's recommendation was measured but firm. Governments needed to manage their debt carefully. They should build cash reserves for emergencies. They should use the current environment of low interest rates to extend the maturity of their bonds—locking in cheap financing for longer periods, reducing the risk that they would be forced to refinance at higher rates when central bank support faded. Cristina Casalinho, who headed Portugal's debt management agency, had already signaled that this was the strategy her country would pursue.
The deeper tension was European. The EU's Stability and Growth Pact, which normally limits how much member states can borrow and spend, had been suspended during the pandemic. That escape valve had allowed countries to respond to the crisis without violating the rules. But it could not stay suspended forever. Eventually, the rules would return. And when they did, Europe would face a reckoning: how to manage debt levels that had grown far beyond what the old rules allowed, and how to do it without strangling recovery.
Citas Notables
As economies recover and inflation rises, central banks may reduce their accommodation of debt purchases, exposing highly indebted countries to rising financing costs— OECD report
Central banks should use the current low-rate environment to extend bond maturities and reduce refinancing risks— OECD recommendation
La Conversación del Hearth Otra perspectiva de la historia
Why did central banks need to buy half of all this new debt? Couldn't governments just sell bonds to investors?
Investors were frightened. No one knew how deep the crisis would go. Central banks stepped in to guarantee there would always be a buyer, and to keep interest rates low so governments could borrow cheaply. Without that, borrowing costs would have spiked and countries couldn't have afforded to spend what they needed to.
So this was temporary crisis management?
That was the theory. But now central banks own enormous chunks of government debt. When they eventually sell or stop buying, the market has to absorb all that supply. If investors don't want it at the same low prices, rates go up.
And that's the trap for countries like Portugal?
Exactly. Portugal borrowed heavily during the pandemic when rates were cheap and central banks were buying. Now it's the third most indebted country in the eurozone. If central bank support disappears and rates rise, refinancing that debt becomes much more expensive.
Could they just keep the support going indefinitely?
The OECD doesn't think so. As economies recover, inflation will rise. Central banks will need to tighten policy to control it. They can't keep buying bonds forever without stoking price increases.
What's the way out?
Lock in the low rates now. Extend the maturity of bonds so you're not forced to refinance at higher rates later. Build cash reserves. Manage carefully. It's not glamorous, but it's what the OECD is recommending.