Interest Rates: The Common Map Connecting Financial Markets
When stock prices rise, it is attributed to “falling interest rates,” and when the yen is sold, it is attributed to the “interest rate gap between Japan and the U.S.” The same word, interest rate, also appears in news about mortgages and savings. So, how are the interest earned on money in a bank and the stocks and currencies traded around the world connected?
Interest rates are the price of time for money
In short, an interest rate is the price attached to using money for a certain period, or to waiting instead of using it.
Ten thousand yen today and ten thousand yen a year from now do not necessarily have the same value, even if the amount is the same. For the person depositing, interest is a reward for waiting. For the person borrowing, it is a fee for being able to use the money ahead of time.
When this “price attached to time” changes, the conditions for choosing whether to deposit, borrow, use now, or save for the future change. Furthermore, it also affects decisions on whether to keep funds domestically or move them overseas.
Thinking about four types of interest rates separately
The interest rates that appear in the news are not all the same.
The policy interest rate is the short-term interest rate set by the central bank as the core of its monetary policy. The central bank plays the role of adjusting the flow of money and interest rates for the entire country.
Market interest rates are rates that fluctuate in markets where government bonds and corporate bonds are traded. These incorporate expectations for future economic conditions and prices. A government bond is a type of IOU issued by the government, and a corporate bond is a type of IOU issued by a company.
Deposit interest rates are the rates received when money is deposited in a bank. Lending interest rates are the rates paid on mortgages and corporate loans.
Even if the central bank changes the policy interest rate, not all interest rates move mechanically by the same margin. Each interest rate is determined by a combination of market expectations, bank competition, and the creditworthiness of borrowers.
From the central bank to households and companies
A major role of the central bank is to prevent prices from becoming too unstable and to soften the impact when the economy cools down or overheats rapidly.
When the economy is weak and price increases are sluggish, they lower interest rates to make borrowing easier and try to support consumption and investment. Conversely, when price increases are too strong, they raise interest rates to curb the momentum of borrowing and spending.
However, the effects of policy do not necessarily reach households immediately. They are transmitted to the economy with a time lag, passing through the central bank’s decisions, banks’ lending stances, and market expectations.
If interest rates rise, the repayment burden on variable-rate mortgages is likely to increase. Households might postpone spending on travel or furniture. On the other hand, if interest on deposits increases, the appeal of keeping money in the bank without using it grows.
For companies, borrowing for capital investment and new business projects becomes heavier. Even if profits remain the same, if interest payments increase, the profit remaining on hand decreases. Interest rates reach the real economy not just through bank screens, but through household wallets and corporate investment plans.
Thinking about stock prices in terms of profit and present value
There are two main paths through which interest rates affect stock prices.
One factor is corporate earnings. When interest rates rise, borrowing costs increase, which can dampen consumption and capital investment, potentially lowering future profit forecasts.
Another factor is the calculation used to convert future earnings into present value. Stocks are assets that price in future earnings in advance. When converting a future sum of 10,000 yen into its current value, a higher benchmark interest rate results in a lower present value.
Therefore, rising interest rates tend to be a headwind for stock prices, both through the impact on earnings themselves and through the method used to value those earnings.
So, does a drop in interest rates always lead to higher stock prices? Not necessarily. Low interest rates can increase the appeal of shifting funds from deposits and bonds into stocks, and can also make it easier for companies to raise capital, which may work to push stock prices higher.
However, if the interest rate cut is a response to a worsening economy, corporate earnings may decline. While it may be a tailwind for valuation, it can be a headwind for earnings. Stock prices reflect not only interest rates, but also the reasons behind interest rate movements and the outlook for corporate earnings simultaneously.
Foreign exchange is a market for choosing currencies
In the foreign exchange market, the yen or the dollar itself does not generate profit like a company does. Investors compare the expected returns on assets held in those currencies.
When interest rates in a particular country rise relative to others, deposits and bonds in that country may appear more attractive, leading to an increase in funds used to purchase that currency. Conversely, there are transactions where investors borrow a low-interest currency to buy assets in a high-interest currency. This is known as a carry trade.
However, it cannot be said that a widening interest rate gap will always lead to a stronger currency. The meaning changes depending on whether the high interest rate reflects economic strength or is simply compensation for concerns regarding inflation or fiscal health.
The market prices in future interest rate expectations before the actual announcements are made. If a rate hike occurs as expected, the market may not move much at the time of the announcement. Conversely, a single unexpected remark can cause stocks, bonds, and currencies to move simultaneously.
Unexpected connections: Investment booms and shifts in capital allocation
When trying to understand investment booms, one should not look at interest rates as the sole cause.
The reduced appeal of deposits due to low interest rates. Increased awareness of the purchasing power of cash due to rising prices. Higher expectations for corporate earnings and stock prices. The ease of starting investments via smartphones. The expansion of tax systems that encourage long-term investment.
When these factors combine, a flow of funds from deposits into investment products is created. However, an increase in the number of accounts is different from the actual amount of capital invested. It is also necessary to verify whether account balances have increased due to price appreciation.
What becomes clear here is that news about stocks, bonds, currencies, and deposits are not separate events. When viewed as a market where investors and households choose where to allocate their capital, the movements of each become connected.
Four questions to ask when looking at interest rate news
When you see news about a “rate hike” or “rate cut,” try checking the following four points.
-
What is happening with prices and employment?
-
What impact will this have on household deposits and borrowing?
-
How will corporate earnings and future values change?
-
Where are domestic and international interest rate differentials likely to move funds and currencies?
Following this sequence allows you to track not just the results—such as ‘stock prices rose’ or ‘the yen fell’—but also the flow of funds that preceded them.
Of course, looking at interest rates does not mean you can predict the future of the market. Stock prices are influenced by corporate technological innovation and earnings, exchange rates by politics and overseas conditions, and interest rates by confidence in prices and fiscal policy. Because markets move by anticipating the future, prices can sometimes move before interest rates change.
The important thing is not to memorize ‘rate hikes mean lower stock prices.’ It is to break down and consider how interest rates make financing more burdensome for some, change the attractiveness of certain assets, and shift demand for specific currencies.
Conclusion—Interest rates are a map that connects choices
Why do deposit interest rates connect to news about stock prices and exchange rates?
Interest rates are transmitted from central bank policy to the market, changing deposits and lending. They alter household spending and corporate profits, change the present value of future earnings, and move stock prices. At the same time, they change the attractiveness of domestic and international assets, moving exchange rates through the flow of funds. These environmental changes also influence how investment booms spread.
In short, interest rates are a common benchmark in financial markets that change the conditions for choices: whether to use funds now, deposit them, invest them in companies, or move them into another currency.
When you see the news, try to think not just about the rise or fall of numbers, but about whose choices those numbers have changed. Market price movements can be seen as the footprints left by people, companies, and capital making new choices.