Federal Reserve officials saved the European banking sector from total collapse in 2008 by opening unlimited dollar exchange windows for foreign central banks who desperately…

Why European banks ran short of dollars

Banks in Europe had borrowed heavily in dollars to finance investments and loans, including US mortgage-related assets. When lenders stopped trusting one another during the 2008 crisis, short-term dollar lending dried up. Yet dollar debts still came due, and selling assets quickly could deepen losses and push more institutions toward failure.

The problem was not simply that Europe lacked money in general. A bank with euros could not automatically use them to repay a dollar loan. Converting large sums in panicked currency markets could also be difficult or costly.

How a central-bank swap supplied dollars

The Federal Reserve arranged currency swap lines with foreign central banks, including the European Central Bank. In a swap, the Fed provided dollars to the partner central bank in exchange for an equivalent amount of its currency, at an agreed exchange rate. The foreign central bank then lent those dollars to banks in its own jurisdiction, typically against collateral and at interest.

At the agreed end of the transaction, the two central banks reversed the exchange. The foreign central bank—not the private borrower—was responsible for returning the dollars to the Fed. That structure let the Fed address a shortage in dollar funding without choosing individual European banks as its direct borrowers.

A backstop, not a rescue of every bank

The arrangements helped keep dollar payments and lending functioning when private markets were retreating. They also reassured lenders that banks with sound collateral could still obtain dollars, reducing pressure to sell assets at fire-sale prices. The lines were expanded during the crisis, and their availability was not limited to a small, fixed pool in the way ordinary emergency lending might be.

But swap lines did not erase banks’ losses or make every borrower safe. They supplied temporary funding; they could not repair insolvent institutions or restore confidence by themselves. Their striking consequence was that a central bank on one side of the Atlantic could stabilize dollar funding far beyond its own borders, because so much international borrowing depended on the US currency.