What Negative Euro and Yen Basis Says About Dollar Stress

What is the cross-currency basis?

In global finance, the US dollar is the currency everyone seems to need. When that need becomes urgent, a little-known indicator starts flashing: the cross-currency basis. In particular, the negative euro and yen basis has become a signal of dollar funding stress. Here is how to read it.

Start with an FX swap, a workhorse of global markets. In an FX swap, one party borrows one currency and simultaneously lends another. Say a European company needs dollars for a year. It lends euros to a bank and borrows dollars; at maturity, both sides repay what they borrowed, at a forward rate agreed at the start. This is a way to obtain dollars while avoiding open currency risk. FX swaps are most liquid at maturities under one year, while longer-term needs often use cross-currency basis swaps, which run from one to thirty years and include periodic exchanges of interest payments.

A cross-currency basis swap works similarly but also involves exchanging floating interest payments over the life of the contract. It is commonly used by financial institutions, multinational companies and bond issuers to fund foreign-currency investments or convert liabilities.

In an ideal textbook world, swapping into a currency should cost the same as borrowing it directly. That idea is called covered interest parity. It holds that the interest-rate difference between two currencies should equal the difference between the forward and spot exchange rates. If that relationship breaks, arbitrageurs could, in theory, make a riskless profit. Since the 2007-08 financial crisis, however, covered interest parity has been violated, and the price of that violation is the cross-currency basis.

What a negative basis is telling you

The cross-currency basis is the adjustment between the cost of borrowing dollars through a swap and the cost of borrowing dollars directly in the cash market. A zero basis means the two are equal. A negative basis, as seen for the euro and yen against the dollar since 2007, means borrowing dollars through the swap market is more expensive than borrowing dollars directly. In other words, the market is charging a premium for dollar access.

Why? Because more participants want dollars through swaps than there are counterparties willing to supply them. In general, the more negative the basis, the more severe the dollar shortage. The premium is usually expressed in basis points, where one basis point is one-hundredth of a percentage point.

Here is an example of how it works. Imagine a European company with a one-year swap. Suppose dollar interest is 1.6% and the euro interest rate is -0.4%. According to covered interest parity, the theoretical cost of the swap is 2%. If a dollar shortage makes the counterparty quote a basis of -50 basis points, the company's actual cost rises to 2.5%. That extra 0.5 percentage point is the price of getting dollars when dollars are in high demand.

Why the euro and yen basis is negative

The negative basis is not new. It emerged during the 2007-08 crisis and, surprisingly, stayed even after crisis strains faded. It widened again after 2014, driven by hedging demand from banks, investors and bond issuers, even as bank balance sheets strengthened. In other words, it can reflect structure, not just panic.

One source of pressure is banks. In Japan, banks have used a large domestic base of yen deposits to fund expansion abroad, much of it in dollars. They manage the currency mismatch through the FX swap market, which keeps steady pressure on the yen/dollar basis. In the euro area, another source appeared after the European Central Bank's bond-buying programmes compressed euro corporate credit spreads. US firms found it cheaper to issue bonds in euros and then swap the proceeds into dollars. These "reverse yankee" issues increased demand for cross-currency swaps, pushing the euro/dollar basis more negative.

Institutional investors also play a role. Insurance companies and pension funds often hedge foreign-currency investments with swaps, and their hedging needs do not disappear just because the basis becomes costly. So the negative basis can be a persistent, structural market feature, not simply a crisis alarm.

Why doesn't arbitrage close the gap?

If dollars are more expensive through swaps than in cash markets, why don't banks rush in to profit and erase the gap? The short answer: arbitrage is not as free as textbooks suggest. It requires balance sheet space, and balance sheet space is rented, not free. A bank that tries to exploit the basis must deploy capital, take on counterparty risk, and reserve room on its balance sheet. Since the financial crisis, banks manage those costs more tightly. Regulation and shareholder pressure make them less willing to expand leverage for what used to look like a low-risk trade. As a result, when hedging demand pushes the basis negative, arbitrage no longer automatically snaps it back to zero.

There is also a link with the dollar's strength. Research has described a three-way relationship: a stronger dollar tends to be accompanied by larger deviations from covered interest parity and by contractions in cross-border bank lending in dollars. The dollar can be seen as a proxy for the shadow price of bank leverage, meaning that when banks' capacity to lend in dollars becomes more constrained, the basis widens.

The central bank backstop

Because a severe dollar shortage can disrupt credit for households and businesses, central banks have built a safety net. The Federal Reserve has standing dollar liquidity swap lines with the European Central Bank, Bank of Japan, Bank of England, Bank of Canada and Swiss National Bank. In a swap-line operation, the Fed lends dollars to a foreign central bank and receives the foreign currency as collateral. The foreign central bank then lends those dollars to institutions in its own jurisdiction, and it bears the credit risk. The Fed's contract is with the central bank, not with private banks. Because both legs of the swap use the same exchange rate, the operation carries no exchange-rate risk for the Fed.

These lines are not a hypothetical tool. They were first used intensively during the global financial crisis, when swap drawings peaked at over $580 billion in December 2008. They were renewed in 2010 and made standing in 2013. In March 2020, as the pandemic strained markets, the Fed lowered the pricing on the swap lines and added temporary lines with nine more central banks. Usage peaked in May 2020 at about $470 billion, with around 80% going through the European Central Bank and the Bank of Japan. In March 2023, the network increased the frequency of seven-day dollar operations from weekly to daily. The purpose is always the same: provide a direct source of dollars, cap the cost of private-market dollar borrowing, and help keep credit flowing.

The signal, not the story

For an ordinary reader, the cross-currency basis is like a thermometer. It tells you when dollar funding is under pressure, but it does not by itself say what will happen next. A negative euro and yen basis can coexist with calm markets, or it can flare up during a crisis. It is a measure of demand and cost, not a preordained outcome. No one can reliably forecast where the basis will go, and market rules differ across jurisdictions. The useful habit is to hear "negative basis" not as a mystery but as a message: the world is paying extra to get dollars, and central banks are standing by to ease the pressure if needed.