Japan Is Collapsing What It Mean For The United States
- Jonathan molendijk
- Aug 13
- 9 min read
Japan’s currency problem is not a simple story of “money collapse.” It is a story of a weak yen, a central bank trying to exit decades of ultra-low interest rates, and a global trade that may become dangerous if it unwinds too quickly.
For years, investors could borrow Japanese yen at very low cost and buy higher-yielding assets elsewhere, especially in the United States. That trade worked as long as Japan kept rates near zero and the yen stayed weak or stable. Now the Bank of Japan has started to move away from that policy. If yen funding becomes more expensive, or if the yen suddenly strengthens, the carry trade can reverse.
That matters for the US because parts of the global financial system are connected by borrowed money, currency swaps, Treasury holdings, and risk appetite. A sharp yen move can force investors to sell US assets, reduce dollar liquidity, and create stress in markets that look unrelated at first glance.
This article is for informational purposes only and is not financial advice.
Japan’s yen problem is really an interest rate problem
The yen weakened because Japan stayed near zero rates while the US and other major economies raised rates aggressively after the inflation surge of 2021 and 2022.
The Federal Reserve raised its policy rate to the highest level in more than two decades. The Bank of Japan, by contrast, kept monetary policy extremely loose for far longer. Japan had spent years fighting low inflation and weak growth, so the BOJ was reluctant to tighten too soon.
That gap created a powerful incentive:
Borrow yen cheaply.
Convert yen into dollars.
Buy US assets that pay higher returns.
Profit from the rate gap, as long as the yen does not rise too much.
This is the carry trade.
The Interest rate differential (Fed vs. BOJ) became one of the biggest forces behind yen weakness. When US short-term rates sit far above Japanese rates, investors get paid to hold dollars instead of yen. That pushes capital away from Japan and into higher-yielding markets.
The yen’s slide also became politically sensitive inside Japan. A weaker currency makes Japanese exports more competitive, but it raises the cost of imported energy, food, and raw materials. Japan imports much of its energy, so a weak yen hits households and businesses through higher import prices.
This is why the Ministry of Finance and the Bank of Japan matter so much. The BOJ controls monetary policy. The Ministry of Finance has authority over currency intervention. Japan has used yen-buying intervention before, including in 2022, when the yen fell sharply against the dollar.
The issue is that intervention can slow a move, but it usually cannot change the trend unless interest rate pressure changes too.
The Bank of Japan finally changed course
Japan’s policy shift became clearer in 2024. The Bank of Japan ended its negative interest rate policy in March 2024, which was widely reported as its first rate hike since 2007. That was a major symbolic break from years of emergency settings.
The BOJ also began moving away from yield curve control, the policy it used to cap or guide Japanese government bond yields. For years, that policy helped keep borrowing costs low. It also made Japan stand out from the US and Europe, where central banks had tightened much more.
The challenge is that Japan cannot raise rates too quickly without creating problems at home.
Japan has one of the world’s largest public debt burdens relative to GDP. Higher rates can raise government borrowing costs over time. Banks, insurers, pension funds, and households also hold large amounts of Japanese government bonds. A fast rise in yields can create mark-to-market losses and stress in the financial system.
So the BOJ is walking a narrow path:
If it keeps rates too low
If it raises rates too fast
The yen may keep weakening, import costs rise, and confidence can fall.
Bond markets can become unstable, debt-service costs rise, and the economy may slow.
This is why the phrase “Japan’s money is collapsing” needs care. The yen has weakened severely, and Japanese purchasing power against the dollar has fallen. But Japan is not a failed monetary state. It is a rich, developed economy with deep capital markets, a major central bank, and large foreign assets.
The danger is not that the yen disappears. The danger is that the adjustment becomes disorderly.
What the yen carry trade actually is
The yen carry trade sounds complicated, but the basic math is simple.
Japan had very low borrowing costs. The US had much higher yields. If an investor could borrow yen at a low rate and buy US Treasury bills, corporate bonds, stocks, or other assets with higher expected returns, the spread was attractive.
The trade worked even better when the yen weakened. If an investor borrowed yen, sold yen for dollars, then later paid back the yen loan after the yen had fallen, the currency move added to the gain.
A simplified example shows the appeal.
An investor borrows yen at a very low rate. The investor converts that money into dollars and buys a US asset yielding around 5%. If the yen stays weak, the investor earns the yield difference. If the yen falls, the investor may also gain on the currency conversion.
But the same trade can turn quickly.
If the BOJ raises rates, yen borrowing costs rise. If the yen strengthens, investors need more dollars to buy back yen and repay loans. If risk assets fall at the same time, the losses can feed on each other.
That creates forced selling.
Investors may sell US stocks, Treasury bonds, corporate debt, or emerging-market assets to reduce exposure and repay yen funding. The trade that once pushed money into global markets can pull money back out.
This is why the carry trade is less like a normal investment and more like a crowded bridge. It can handle steady traffic. It becomes dangerous when everyone tries to leave at once.
Why the US is exposed to a yen carry trade unwind
The US is not directly dependent on the yen, but it is exposed through markets.
The dollar sits at the center of global finance. US Treasuries are the world’s main safe asset. US stocks are heavily owned by global investors. Wall Street also intermediates a large share of currency and funding activity.
A yen carry unwind can affect the US through several channels.
Forced selling can hit US stocks and bonds
When investors unwind carry trades, they often sell liquid assets first. US equities and Treasuries are among the most liquid assets in the world.
That does not mean the yen alone can crash the US market. It means a rapid yen move can add pressure during periods of already weak sentiment.
Large funds do not always sell what they want to sell. They sell what they can sell. US assets are easy to sell, which makes them vulnerable during global deleveraging.
Treasury yields can move in confusing ways
Japan is one of the largest foreign holders of US Treasury securities. Japanese institutions, including insurers and pension funds, often compare US yields with Japanese yields after hedging currency risk.
If Japanese yields rise, some investors may find domestic bonds more attractive. If currency hedging costs are high, US bonds may look less appealing. That can reduce demand for Treasuries at the margin.
At the same time, a global risk shock can push investors into Treasuries as a safe haven. So yields could rise because foreign demand weakens, or fall because panic buying increases. The direction depends on which force dominates.
Dollar funding can tighten
The phrase Global dollar shortage refers to moments when borrowers outside the US struggle to get dollars. Many global loans, trades, and investments are dollar-based, even when the borrower is not American.
If yen-funded investors need dollars to cover losses, repay financing, or meet margin calls, demand for dollars can jump. That can tighten global funding conditions.
During past stress periods, such as the 2008 financial crisis and the March 2020 COVID market shock, the Federal Reserve opened or expanded dollar swap lines with major central banks to ease dollar funding pressure. Japan’s central bank is one of the major institutions in that network.
That history shows how currency stress can become a dollar problem.
Currency intervention can buy time, but not solve the gap
Japan’s Ministry of Finance has the authority to intervene in foreign exchange markets, while the Bank of Japan acts as its agent. In plain English, Japan can sell dollars and buy yen to support its currency.
This is known as yen-buying intervention.
It can work in the short run because it shocks traders and makes one-way bets riskier. Japan has large foreign exchange reserves, so markets take intervention seriously.
But intervention has limits.
If the US pays much higher interest than Japan, investors still have a reason to hold dollars. If energy imports remain expensive, Japan still needs foreign currency. If markets believe the BOJ is moving too slowly, pressure can return.
That is why traders watch both policy and price levels. Terms such as Japanese yen depreciation / weakening yenBank of Japan (BOJ) monetary policyFX intervention / yen-buying interventionHistoric yen lows / 38-year low yen all point to the same issue: the currency is caught between market pressure and official resistance.
The most stable fix would be a smaller rate gap. That could happen if the Fed cuts rates, if the BOJ raises rates, or both. But timing matters. If the adjustment is slow, markets may digest it. If it is sudden, carry trades can break fast.
The scary scenario is a disorderly unwind
A controlled yen rebound would not be a crisis. It might even help Japan by reducing import costs and restoring confidence in the currency.
The risk is a violent move.
A disorderly unwind could look like this:
The yen strengthens quickly after BOJ action or suspected intervention.
Carry traders rush to close positions.
Investors sell US and global assets to raise cash.
Margin calls force more selling.
Volatility rises, which causes risk models to cut exposure.
Dollar funding tightens as demand for cash rises.
This is how a currency move can become a broader market event. The trigger may seem small compared with the size of US markets, but leverage changes the math. If many investors use borrowed money, a 2% or 3% currency move can force much larger portfolio changes.
One useful comparison is 1998, when the collapse of Long-Term Capital Management showed how leveraged trades across bonds, currencies, and derivatives could threaten wider markets. The details are different, but the lesson still applies. Crowded trades can look safe until liquidity disappears.
The calmer scenario is a slow adjustment
The better outcome is also possible.
The BOJ can raise rates slowly. The Fed can cut rates if US inflation cools enough. The yen can stabilize without a sharp squeeze. Japanese investors can rebalance gradually rather than all at once.
In that world, the carry trade shrinks instead of snaps.
This would still affect US markets. Treasury demand from Japan could change. The dollar could weaken. US stocks could face less foreign liquidity support. But those shifts would be manageable if they happen over months or years.
The Fed, BOJ, and Ministry of Finance all have tools. The Fed can provide dollar liquidity during stress. The BOJ can manage domestic money markets. Japan’s Ministry of Finance currency policy can push back against extreme yen moves.
The key question is whether markets believe the policy path is credible.
What to watch next
The yen carry trade risk is not about one exchange rate number. It is about the interaction between policy, positioning, and liquidity.
The most useful signals are:
BOJ rate decisions
More hikes would raise the cost of yen borrowing and pressure carry trades.
Fed policy expectations
If US rates are expected to fall, the dollar advantage shrinks.
Dollar-yen volatility
Fast moves matter more than round numbers.
Japanese government bond yields
Rising domestic yields can pull Japanese capital home.
Signs of intervention
Sudden yen strength around key levels can suggest official action, though confirmation usually comes later.
Stress in US risk assets
A yen surge paired with falling stocks and wider credit spreads would be more concerning than a yen move alone.
The main point is simple: Japan’s weak yen is not an isolated currency story. It is tied to the price of money across the world.
For more than a decade, cheap yen helped fuel global risk-taking. If that era ends slowly, markets can adapt. If it ends abruptly, the US could feel it through stocks, bonds, Treasury demand, and dollar funding pressure.
Japan’s money is not collapsing in the cartoon sense. The yen is under strain because the old zero-rate model no longer fits a world of higher global rates. The danger for the US is not Japan’s weakness by itself. It is the possibility that years of yen-funded bets unwind at the same time.
