The Bank of Japan’s FX Intervention: Mechanism, Impact, and Historical Precedent
How the Process Works
Who Decides? The Ministry of Finance (MOF) is the boss. They decide if and how to intervene after looking closely at the currency market.
Who Executes? The Bank of Japan (BoJ) handles the actual buying and selling of currency, following the MOF’s specific orders.
Where Does the Money Come From?
To Make the Yen Stronger (Buying Yen): The MOF uses the government’s existing foreign currency reserves (money saved in U.S. dollars, etc.).
To Make the Yen Weaker (Selling Yen): The MOF has to borrow yen by issuing special government debt called Financing Bills (FBs).
Controlling the Money Supply: Even when the BoJ carries out the trade, it makes sure these currency operations don’t mess up its main goal of controlling the country’s money supply. The intervention is factored into its daily financial planning.
Why Interventions Work (or Don’t)
Currency intervention works in two main ways:
Portfolio Balance (Changing the Supply): This involves changing the amount of different assets (like yen vs. dollars) available in the market.
Signaling (Changing Expectations): This is when the government sends a strong message to traders about what future economic policy will be.
The Big Problem for Japan: Japan has had near-zero interest rates (ZIRP) for a very long time.
Normally, actions that change the money supply (unsterilized intervention) are very effective.
However, under ZIRP, cash and short-term government debt are viewed as almost the same thing. This means changing the money supply doesn’t have its usual big impact.
The Key to Success: Because the first method is weakened, the success of Japan’s currency intervention depends almost entirely on the Signaling channel. The government must show strong credibility and commitment to back up its currency trades with future policy action.
The Limit: Intervention cannot permanently overcome powerful economic forces, such as the persistent difference between Japan’s low interest rates and higher rates in other countries. It is only a temporary tool to reduce quick and extreme price swings.
