Currency Intervention: When Central Banks Sell Their Own Money
Macro Glossary, Sentiment and Regime
By Ken Chigbo, macro trader and founder of KenMacro, 18+ years in markets.
Updated 2026-05-20
The desk’s answer
Currency intervention is direct action by a central bank or finance ministry to influence the FX value of a currency. Three escalating stages: verbal intervention (jawboning by officials), sterilised intervention (actual FX sales offset by domestic operations to keep money supply unchanged), and unsterilised intervention (FX sales that change money supply). The Bank of Japan and Japan’s Ministry of Finance are the most active practitioners, intervening against yen weakness multiple times in 2022 and 2024. The Swiss National Bank intervened heavily against franc strength during the 2011-2015 EUR/CHF floor period. The Federal Reserve rarely intervenes.
Defined term, Currency intervention
Currency intervention is direct action by a central bank or finance ministry to influence the foreign exchange value of its currency, escalating through three stages: verbal jawboning, sterilised intervention (FX sales offset by domestic operations to keep money supply unchanged), and unsterilised intervention (FX sales that change money supply). The Bank of Japan and Ministry of Finance are the most active practitioners against yen weakness; the Swiss National Bank has used it heavily; the Federal Reserve rarely intervenes.
How intervention is escalated
Three stages, usually in sequence. First, verbal intervention: a senior official (Finance Minister, Central Bank Governor, currency-policy chief) makes a public statement that the currency move is ‘excessive’ or ‘one-sided’ or ‘inconsistent with fundamentals’. This is essentially free and works in calm regimes by changing market expectations. Second, sterilised intervention: the central bank sells (or buys) FX reserves in the spot market but offsets the domestic-money-supply effect through reverse operations (selling government bonds to absorb the yen created by FX purchases). Third, unsterilised intervention: FX operations without the sterilising offset, which changes domestic money supply and is closer to outright monetary easing or tightening. Unsterilised is the most powerful but used rarely.
BoJ intervention against yen weakness
The Bank of Japan acting on behalf of Japan’s Ministry of Finance has intervened against yen weakness multiple times since 2022, with USD/JPY interventions in September 2022 (around 145), October 2022 (around 152), April-May 2024 (around 160), and July-August 2024 (around 162). Each intervention produced an immediate 4 to 7 percent USD/JPY drop, with the move usually fading 50 to 80 percent over the following weeks unless reinforced by changing fundamentals. Verbal intervention by Vice Finance Minister for International Affairs (the ‘currency tsar’) often precedes actual intervention by days to weeks.
How to trade around intervention
Three rules. First, recognise the verbal-intervention escalation pattern early: when officials shift from observing the move to using stronger language (‘one-sided’, ‘speculative’, ‘will take decisive action’), the timeline to actual intervention is days, not weeks. Second, size positions for the intervention size move: yen interventions have historically produced 3 to 7 percent moves in hours, which on a leveraged short-yen position can wipe out an account. Third, the fade trade after intervention often works in calmer regimes: the immediate move typically reverses 50 to 80 percent in the weeks after as fundamentals reassert. Verify positioning data before placing the fade; if hedge funds covered shorts at the intervention, the fade is much weaker.
Frequently asked
What is currency intervention?
Direct action by a central bank or finance ministry to influence the foreign exchange value of a currency. Escalates through three stages: verbal intervention (jawboning), sterilised intervention (FX sales offset by domestic operations), and unsterilised intervention (FX sales that change money supply).
Which central banks intervene most actively?
The Bank of Japan and Japan’s Ministry of Finance against yen weakness (multiple interventions in 2022 and 2024). The Swiss National Bank against franc strength during the 2011-2015 EUR/CHF floor period. The People’s Bank of China manages the daily USD/CNY fix actively. The Federal Reserve rarely intervenes.
How do markets react to BoJ yen intervention?
Immediate 4 to 7 percent USD/JPY drop in hours, with the move usually fading 50 to 80 percent over the following weeks unless reinforced by fundamentals. The 2022 and 2024 BoJ interventions all followed this pattern. The fade trade after intervention often works in calmer regimes but requires checking positioning data first.
What this means at the desk
Watch the verbal escalation. When the Vice Finance Minister gets specific, the intervention is days away, not weeks.
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