[Summary]
Interest is the price of money.
For borrowers, it is a cost. For lenders, it is a return. Mortgages, corporate borrowing, government bonds, bank deposits, foreign exchange, and stock prices all sit on the foundation of interest rates.
So who decides interest rates?
Short-term rates are strongly affected by central bank policy. Long-term rates, however, move with inflation expectations, fiscal conditions, government bond supply and demand, overseas rates, and investor risk perception. Interest rates are not a price decided unilaterally by the central bank.
This chapter treats interest rates as the price of money and examines how the institutional power of central banks and the power of cross-border markets compete over price formation.
This article is a general explanation of interest rates and financial markets. It does not recommend refinancing mortgages, choosing fixed or floating rates, investing in bonds, stocks, or foreign exchange. Actual decisions require checking the latest rates, contract terms, fees, tax treatment, and risk tolerance.
New Price Formation Theory Series
We live surrounded by many prices: stock prices, hourly wages, interest rates, foreign exchange, and the value of data.
Who decides them, and under what rules?
This series reads modern capitalism through the question of who controls the rules of price formation.
- New Price Formation Theory | Who Decides Prices?
- New Price Formation Theory | Capital Markets: Who Decides Stock Prices?
- New Price Formation Theory | Labor Markets: Who Decides Wages?
- New Price Formation Theory | Financial Markets: Who Decides the Price of Money? (this article)
- New Price Formation Theory | Foreign Exchange Markets: Who Decides the Price of the Yen?
- New Price Formation Theory | Data Markets: Who Decides the Price of Data?
Interest Is the Price of Money
When we buy goods and services, we naturally pay in yen, dollars, or other currencies.
But what is the price of money itself?
In economics, the price of money as an asset is interest.
After a long period of very low rates, Japan is moving back toward a world with interest rates. That shift affects mortgages, corporate investment decisions, government bond markets, bank deposits, stock prices, and foreign exchange.
Interest is the discount rate behind almost every market price.
| Position | How rising rates look |
|---|---|
| Mortgage borrower | Repayment burden can increase |
| Company | Borrowing costs can rise |
| Depositor | Deposit rates may rise |
| Bank | Lending margins may improve, but credit costs matter |
| Government | Interest burden on bonds can increase |
| Investor | Valuations of stocks, bonds, and real estate are affected |
In the capital markets chapter, we saw stock prices as a mechanism that prices future expectations and risk. In the labor markets chapter, we saw wages as a price that the state tries to protect through competition rules.
Now the question is: who decides the price of money that sits beneath both?
The answer reveals a major paradox of modern capitalism, where market supply and demand coexist with the powerful actor called the central bank.
1. The Price That Governs Other Prices
To understand why interest rates are the price of money, we need to look at how future value is translated into present prices.
Capital markets do not value companies only by past results. They buy future profits, future control, and future survival probability.
But one hundred million yen in the future is not the same as one hundred million yen today. To translate future profits into present stock prices, we need a yardstick for discounting future value.
That yardstick is the interest rate.
When the price of money changes, assumptions about discount rates change. The theoretical values of stocks, real estate, corporate investment, M&A, government bonds, and mortgages all move in chain reaction.
Interest rates are not merely a financial term.
They are a hidden baseline that shapes many prices from behind.
2. Market Supply And Demand Meets Central Bank Intent
The Bank of Japan explains that it influences interest-rate formation in financial markets through tools such as money market operations and conducts currency and monetary control.
The basic stance of monetary policy is decided at Monetary Policy Meetings of the Policy Board. Based on the policy guideline decided there, the Bank conducts daily market operations.
The key point is that the central bank does not directly decide every interest rate.
Its strongest influence is mainly on short-term money-market rates.
The uncollateralized overnight call rate is the rate on overnight unsecured lending and borrowing among financial institutions in the call market. Since the 1990s, it has often been the main operating target.
In plain language, short-term interest is the price banks pay to borrow money from each other overnight.
By influencing that price, the central bank affects bank funding costs, lending rates, deposit rates, and corporate borrowing costs.
In textbook terms, interest rates are determined by the demand for money and the supply of money. When companies want to invest in a strong economy, demand for funds increases and rates tend to rise. When demand is weak in a downturn, rates tend to fall.
That is the basic market mechanism.
But real financial markets do not move only by pure supply and demand.
This is where central banks such as the Bank of Japan and the Federal Reserve enter.
Central banks do not behave like ordinary market participants seeking profit. Under policy objectives such as price stability and sustainable growth, they influence price formation through policy rates and government bond purchases.
The BOJ's negative interest rate policy and yield curve control were representative examples. Through the monetary system, the central bank deeply intervened in market price formation.
Here lies the paradox.
In financial markets, the core of capitalism, the most important price is not decided only by free market competition. It is designed, corrected, and sometimes suppressed by institutional power.
3. Long-Term Rates Ask The Market's Question Back
Long-term interest rates are more complicated.
The representative long-term rate is the yield on long-term government bonds, often the 10-year JGB yield in Japan.
Government bonds are traded in markets. When bond prices fall, yields rise. When bond prices rise, yields fall.
Central banks can influence long-term yields through bond purchases and policy guidance. But they cannot erase market questions forever.
If inflation expectations rise, if fiscal concerns grow, if overseas rates rise, or if investors demand higher returns, long-term yields can move even against the preference of policy makers.
In other words, short-term rates are heavily shaped by central bank design, while long-term rates incorporate the market's assessment of the economy, inflation, fiscal sustainability, and global capital flows.
This distinction is crucial.
The central bank can set a policy stance. But the market responds by asking whether that stance is consistent with inflation, fiscal reality, and global interest-rate conditions.
4. The Interest-Rate Differential Leads To Foreign Exchange
When Japanese rates are low while U.S. rates are high, capital tends to move toward higher-yielding assets.
That can mean selling yen and buying dollars.
The central bank has strong influence over the domestic price of money. But if that price diverges greatly from global market conditions, the market responds through other prices: foreign exchange and government bond yields.
This is why interest rates connect directly to the next chapter.
Interest rates are not contained inside domestic financial markets. Through capital flows, they spill into foreign exchange.
The price of money becomes the price of the currency.
Conclusion: Interest Rates Are A Joint Product
Who decides interest rates?
The answer is not "the central bank alone" and not "the market alone."
Short-term rates are strongly shaped by the central bank. Long-term rates include market expectations about inflation, fiscal conditions, bond supply and demand, overseas rates, and risk. The government, banks, companies, households, and global investors all become part of the formation process.
Interest rates are a joint product of central banks, markets, governments, banks, companies, and households.
And the friction between central bank intervention and global capital flows inevitably creates the next battlefield.
Next: Foreign Exchange Markets
The next price to examine after interest rates is foreign exchange.
Who decides the value of the yen?
The price of the yen absorbs distortions in interest rates and reflects the state's credibility. Interest-rate differentials, trade balances, investment flows, central banks, government intervention, and market expectations all collide there.
- New Price Formation Theory | Foreign Exchange Markets: Who Decides the Price of the Yen?
- New Price Formation Theory | Data Markets: Who Decides the Price of Data?
Sources
- Bank of Japan, "Outline of Monetary Policy"
- Bank of Japan, "Monetary Policy Releases 2026"
- Bank of Japan, "What Is The Uncollateralized Overnight Call Rate?"
- Bank of Japan, "Price Stability and Monetary Policy"
- This site, "New Price Formation Theory | Who Decides Prices?"
- Checked on: 2026-06-02