How central bank decisions, forward guidance and interventions move currencies

What you will learn

• Why currencies react to the surprise relative to market pricing, not to the decision itself.
• How to estimate the market-implied probability of a rate change from futures pricing.
• What forward guidance is, its main forms, and which communication channels matter.
• How currency interventions work, from verbal warnings to actual trades, with real historical cases.

Explanation

What the ECB and the Federal Reserve (Fed) do and how a policy rate works was covered in the course "Macro" (lesson "Interest Rates and Central Banks: ECB and Fed"). Here the focus is the reaction function of the currency.

Pricing and surprise

Before a meeting, markets "price" the expected decision through instruments such as short-term interest-rate futures and overnight index swaps. If a 0.25 percentage point (25 basis points, bp; 1 bp = 0.01 percentage points) hike is fully priced, the hike itself is not news. The currency moves on the surprise: the difference between what happened and what was priced, including signals about future meetings.

A simple approximation for one meeting: implied probability of a 25 bp hike ≈ (rate implied by futures − current rate) ÷ 0.25.

Hawkish and dovish

Hawkish means leaning towards tighter policy (higher rates, more concern about inflation); dovish means leaning towards looser policy. A rate cut delivered with hawkish language ("this may be the last cut") can strengthen a currency.

Forward guidance

Forward guidance is a central bank's communication about the likely future path of policy. Main forms:

• Qualitative: general wording such as "rates will remain at present levels for an extended period".
• Calendar-based: linked to a date ("at least through the summer").
• State-contingent or data-dependent: linked to conditions ("until inflation is sustainably at target").

Key channels to read: the policy statement (compare wording with the previous one), the press conference, the minutes or "accounts" published weeks later, speeches between meetings and, for the Fed, the quarterly Summary of Economic Projections with the "dot plot" of officials' rate expectations. The ECB's Governing Council and the Fed's FOMC (Federal Open Market Committee) each hold eight scheduled monetary policy meetings a year; always check the current calendar on their websites.

Currency interventions

A currency intervention means that the authorities buy or sell their own currency to influence its value. It usually escalates in stages:

1. Verbal intervention: officials warn about "excessive" or "disorderly" moves.
2. Rate check: the central bank asks dealers for prices, a signal that action is near.
3. Actual intervention: buying or selling in the market. In Japan, the Ministry of Finance decides and the Bank of Japan carries it out.

Sterilised intervention is offset by other operations so that the money supply does not change; its effect often fades unless policy also changes. Historical cases: in September 2022 Japan bought yen for the first time since 1998, with reported spending of about $20 billion that month. On 15 January 2015 the Swiss National Bank ended its minimum exchange rate of 1.20 francs per euro and cut its deposit rate to −0.75%; the franc jumped within minutes, and many stop orders were filled far from their levels.

Worked example

Hypothetical example: current policy rate 3.00%. Futures imply 3.15% after the meeting. A trader is long the currency with 0.8 lots. Assumptions are illustrative; spreads, slippage and the exact futures mechanics are simplified.

1. Implied probability of a 25 bp hike: (3.15 − 3.00) ÷ 0.25 = 0.60, about 60%.
2. Scenario A: hike with neutral guidance. About 60% was priced, so the surprise is moderate; a modest rise in the currency is plausible, but not guaranteed.
3. Scenario B: no hike, guidance "rates have peaked". The 60% probability must be removed and future hikes repriced: a dovish surprise, likely negative for the currency.
4. Scenario C: no hike, but "a hike at the next meeting is likely". Mixed: the decision disappoints, the guidance supports. Expect two-way volatility.
5. Risk plan: spreads can widen strongly at the release. The trader halves the position from 0.8 to 0.4 lots before the event, accepting that gaps can still exceed a stop.

Common mistake

Practice activity

On paper: (1) The policy rate is 2.00% and futures imply 1.90% for after the meeting. What cut probability is priced? (2) The bank cuts by 25 bp and says further cuts are likely. Is this hawkish or dovish relative to pricing? (3) Officials of a country say they are "watching currency moves with a high sense of urgency". Which intervention stage is this?

Key takeaways

• Currencies move on the surprise against market pricing, including signals about future meetings.
• Implied probability ≈ (implied rate − current rate) ÷ size of the step.
• Forward guidance can be qualitative, calendar-based or state-contingent; compare wording with the previous statement.
• Interventions escalate from verbal warnings to rate checks to actual trades, and can cause gaps that skip stops.

Next step

In the next lesson you will study pegged and managed currencies such as the CNY, HKD, SAR and AED, and the risks of de-pegging.