Transatlantic Rate Convergence May Be a Mirage as Longer-Term Divergences Persist

The gap between American and European interest rates is closing—or so it appears. By the end of this year, the Federal Reserve's policy rate premium over the European Central Bank could vanish entirely. Money markets are pricing in at least two ECB rate increases, with bets clustering around 2.6 percent by December. The Fed, meanwhile, is expected to hold steady this week, with Jerome Powell presiding over what will likely be his final meeting as chair before his term ends on May 15. On the surface, this convergence looks like a powerful headwind for the dollar, which has enjoyed a brief safety rally over the past two months but may struggle to sustain it if the rate advantage disappears.

But look past the near-term numbers and a different story emerges—one that suggests the apparent convergence is an optical illusion masking deeper, more stubborn divergences. The Iran war and the oil shock it triggered have scrambled inflation expectations and policy horizons on both sides of the Atlantic. The euro-dollar pair remains the world's most pivotal currency market, channeling more than two trillion dollars in daily turnover and accounting for more than a fifth of global flows. What happens in the transatlantic rate differential matters far beyond academic interest.

The immediate pressure on the ECB is real and mounting. One-year euro zone consumer inflation expectations surged to 4 percent in March, according to data that has hawks within the central bank pushing hard for action. Frank Flight, a strategist at Citadel Securities, argues that a 50-basis-point catch-up hike in June is not out of the question if the ECB holds rates steady this week and the Gulf conflict persists. The ECB has been in what observers call its "happy place" since June of last year—sitting at a 2 percent official deposit rate with roughly zero real short-term rates—but that comfort is now under siege. The euro zone is facing stagflationary headwinds: tightening bank credit combined with sharply elevated inflation expectations point toward slower growth and higher prices over the longer term.

The Fed's position is different. Inflation remains stuck above its 2 percent target, first aggravated by tariffs and now by fuel prices over the past eight weeks. The futures market assigns less than a 20 percent probability to another rate cut in the next year, with the Fed's mid-rate currently at 3.625 percent. Yet there is a significant drop priced into rate expectations by the end of next year—presumably as the oil shock dissipates and the incoming administration's policies take shape. The upshot is an outside chance that policy rates converge toward 3 percent by then.

Here is where the mirage becomes visible. Two-year government bond yield differentials between the two regions have squeezed to their tightest in almost five years. The real two-year rate gap fell below 50 basis points for the first time in four years. But stretch the horizon to ten years and the picture inverts. The gap in nominal yields remains substantial, and when adjusted for inflation, the real ten-year rate gap is actually widening since the Iran war began. This is not a temporary blip. It reflects structural realities that have persisted for more than a decade.

Setting aside the pandemic—when all major central banks cut to near zero—Fed policy rates have consistently exceeded ECB equivalents for over ten years, driven largely by superior American growth and equity market performance. That advantage is not disappearing. The tech and artificial intelligence booms, combined with elements of deregulation, are expected to run the U.S. economy hotter over the longer horizon. Wall Street stocks surged despite the Iran-related energy crunch, a divergence that Goldman Sachs strategists help explain: terminal value—profits expected more than ten years into the future—now accounts for roughly 75 percent of the S&P 500's total equity value, near a 25-year high. The ECB was quicker to return post-pandemic inflation to target, but it faces a region with weaker long-term growth prospects and persistent inflation risks.

The convergence in short-term rates, then, is real but shallow. It reflects the immediate shock of the Iran war and the oil market disruption, not a fundamental realignment of the transatlantic economy. As that shock dissipates and the longer-term drivers reassert themselves, the old pattern is likely to reassert as well. The more things change on the surface, the more they seem to stay the same beneath.