How Central Banks Talk About Future Rates — and Why Markets Listen

Imagine a friend who tells you, "I'll be at the station by six." Now imagine another who says, "I'll head over once traffic clears." Both are being honest. But only the first gives you something to plan around — and something to blame if it falls apart. Central banks face a version of this choice every time they speak about interest rates, and the way they speak turns out to matter for everyone from mortgage borrowers to currency traders.

Two ways to say "we'll see"

Forward guidance is a central bank telling the public about the likely future path of monetary policy. The Federal Reserve describes it as a tool for signalling where policy is probably headed, so households and businesses can make spending and investment decisions today. The European Central Bank began using it in July 2013, when its Governing Council said it expected rates to stay low "for an extended period."

Data dependence is the alternative: decisions are conditional on incoming information rather than a pre-announced path. As one analysis puts it, this signals flexibility — a refusal to lock in too early. Both approaches are forms of communication. The difference lies in how much certainty each one projects, and how markets respond when that certainty meets reality.

Why expectations move markets at all

Long-term interest rates — the ones that shape mortgages and much business borrowing — are set in bond markets, not directly by the central bank. But they reflect what markets expect short-term rates to do in future. A central bank that can shape those expectations can influence borrowing costs before it changes a single rate. As former Fed chair Ben Bernanke once quipped, monetary policy is "98% talk and 2% action."

This is why communication regimes matter for FX volatility — the way currency prices swing. If markets believe they know the path ahead, they price it in and settle. If the path suddenly looks less certain, positions get unwound, sometimes quickly. Certainty, in other words, can quietly accumulate risk.

The trouble with being too precise

Former Fed governor Jeremy Stein made a sharp observation: perceived certainty about the rate path can encourage leverage and risk-taking, because participants stop seeing risk in the short-term leg of a carry trade. Volatility gets damped — until circumstances force the central bank to deviate, and then it spikes. He pointed to the Fed's 2004–06 promise to raise rates "at a measured pace," which came to mean a near-automatic quarter-point per meeting. It worked, perhaps too well. Greenspan later called the puzzle of barely-rising long yields a "conundrum."

Fed governor Michelle Bowman made a related point in 2022. With inflation high and the outlook unusually uncertain, she argued the benefits of explicit guidance were lower and the costs higher than in the post-2008 years. Guidance that had set a high bar for raising rates, she suggested, may have kept policy too accommodative for too long as conditions shifted.

The older vocabulary is useful here. Delphic guidance, named for the oracles of Apollo, offers forecasts without commitment. Odyssean guidance, named for Odysseus lashing himself to the mast, is an explicit pledge. Odyssean guidance can pack more punch — especially when rates are near zero and the central bank has run out of conventional room — but it also binds the policymaker's hands.

What the evidence says about volatility

Research across 23 countries found that forward guidance tends to reduce the dispersion and error of interest rate forecasts, though less so for macroeconomic forecasts. That fits the idea that markets can read guidance as either a forecast or a promise, and disagree about which.

Recent euro-area evidence adds nuance. When markets perceive the central bank to be in a "high-learning" environment — high uncertainty, repeated forecast errors — rates react more strongly to inflation surprises and less to the central bank's own assessment. Communication stressing that policy isn't driven by individual data points tends to rebalance this. The lesson: talking about uncertainty is not neutral. It is itself a policy choice, and its effects depend on the state of the economy.

Where currencies come in

Rate expectations and currency values are close cousins. When guidance shifts — or when data dependence produces a surprise — exchange rates can adjust as investors reprice the relative attractiveness of holding one currency versus another. That is the channel through which communication regimes feed into FX volatility. It is worth saying plainly: the size and timing of these moves are uncertain, and they vary by jurisdiction, by market conditions and by how much of the guidance was already priced in. Nothing here predicts a particular outcome.

What to take away

Forward guidance and data dependence are not rivals so much as tools with different uses. Guidance can be powerful when rates are stuck near zero and clarity is scarce. Data dependence preserves flexibility when the outlook is murky and forecasts keep missing. The skill lies in matching the message to the moment — and in being honest about how much the central bank actually knows. Which, as any good friend at the station will tell you, is usually less than the timetable suggests.