Japanese Carry Trade at a Breaking Point: Why Stock Indices Remain Resilient Despite Accumulating Risks

Monday’s sharp jump of the Japanese yen to its highest level in two months has triggered a traditional panic reaction in the markets. Instead of a mass sell-off, US stock indices only fluctuated noticeably, maintaining their main positions. This paradoxical phenomenon reveals a critical disconnect between what theory of the “global turnaround of Japanese arbitrage” would suggest and what is actually observed in the markets. The Maitong MSX research center analyzed the current situation and found that the key to understanding this anomaly lies not in obvious price movements but in hidden changes in market structure and conditions that still support arbitrage positions.

Intervention Threshold: Yen rises, but stock indices remain calm

A tiny 1.1% jump in the Japanese yen during early Tokyo trading hours prompted assumptions of direct intervention by Japanese authorities. This was a logical conclusion: firstly, if Japan truly intervened, it would mean acknowledgment of the problem—that the yen is significantly weakened; secondly, such intervention has historically preceded large corrections in equity positions. However, in the following days, US stock indices did not repeat the panic scenarios of previous years.

The last time the country directly intervened in the currency market was in 2024, investing about $100 billion to support the yen at 160. Back then, the market reacted more sensitively. Today, even with a new intervention signal, stock indices demonstrate unusual resilience. This raises the question: is the Japanese arbitrage truly turning around, or is this just an illusion of change?

Theory versus reality: where is the expected wave of selling hiding?

The logic of sudden panic is obvious on paper. If Japan is gradually exiting an extremely accommodative monetary policy, and the Federal Reserve has entered a phase of predictable rate cuts, then theoretically, the gap between US and Japanese rates should narrow. This should dilute the economic basis for arbitrage operations financed by cheap Japanese yen to buy more expensive American assets.

However, the market refuses to follow this scenario. US stock indices have not shown systematic capital outflows. Although global indices fluctuated, there were no typical signs of liquidity panic—sudden foreign capital withdrawals, exit from constrained positions, or rapid trading chaos. This raises a sharp question: if arbitrage positions are truly reversing, why are they not reflected in price structures, capital flows, and stock index behavior?

The key answer lies in a misunderstanding of what “logical deterioration” of the arbitrage environment means. It is not synonymous with “mass capital flight.” Currently, only the first phase of change is occurring: the rate differential is no longer widening, volatility is increasing, and policy uncertainty is intensifying. These factors weaken the relative attractiveness of arbitrage but do not create conditions for forced position closures. For large institutions, the decisive factors are not “words about deterioration” but mathematical ones: whether arbitrage becomes unprofitable, whether nonlinear risk increases occur, or whether tail risk hedging becomes impossible.

Mathematics still favoring arbitrage: why capital remains

As of January 22, 2026, the effective US Federal Funds rate was 3.64%, while the policy rate of the Bank of Japan remained at 0.75% (set in December 2025). The nominal rate difference reached 2.89 percentage points. This means that as long as the yen appreciates less than 2.9% annually, arbitrage operations remain profitable. The morning fluctuation of 1.1% is only a temporary retreat in profit, not a threat to principal capital.

Even more crucial is the calculation of real interest rates adjusted for inflation. In Japan, the real rate is approximately -1.75% to -2.25% (considering inflation at 2.5–3.0%), meaning the borrower effectively loses purchasing power. In the US, the real rate is about 1% (3.64% minus 2.71% inflation). This 3 percentage point difference in real rates strongly supports arbitrage structures more than verbal warnings of intervention. As long as these numbers stay the same, institutional investors have no compelling reason to rush to close positions.

Hidden evolution: how arbitrage operations have become invisible to the ordinary market

Most market participants still perceive arbitrage as a simple chain: yen borrowing → exchange for dollars → purchase of US stocks → waiting for rate differentials and growth. This describes only a small fraction of actual operations. Modern arbitrage trading occurs deep within the structure of financial markets: currency swaps, cross-border basis differentials, systematic currency risk hedging via forward contracts and options. Arbitrage positions often do not exist in isolation but are embedded in multi-factor portfolios, invisible to standard analysis.

This is crucial for understanding why stock indices do not fall as expected: closing arbitrage does not necessarily take the form of explicit selling of US equities and buying yen. Instead, institutions make more subtle adjustments—reducing new capital allocations, temporarily halting expansion of existing positions, decreasing leverage ratios, allowing positions to naturally unwind while holding. The result: capital return manifests as a slowdown in new inflows rather than a clear decline in stock indices. This is a structural feature most market analysts overlook.

When will the real disaster start: three conditions for forced closure

True forced closure of arbitrage positions requires convergence of extreme conditions that the market currently lacks. Historically, to trigger a mass exit from arbitrage, three conditions needed to be met simultaneously: rapid and significant yen appreciation, a simultaneous decline in global risk assets, and a sudden liquidity squeeze in financial markets.

According to CFTC data (U.S. Commodity Futures Trading Commission) as of January 23, 2026, speculative trader net positions in yen stood at -44,800 contracts—much lower than the peak in 2024 (over -100,000 contracts), but still net short. This indicates that speculative funds continue to hold yen short positions and have not yet become net buyers. Until these data turn positive, claims of a “big retreat” remain premature.

Additionally, the震荡 (volatility) experienced in April 2025 (when VIX hit 60) changed the composition of market participants. All funds with leverage over five times were withdrawn from the game. Current participants are survivors from the VIX 60 episode. For them, minor fluctuations of 1.1% do not require margin adjustments, and the market remains calmer than expected.

Structural transformations: how stock indices are losing resilience under a stable surface

Although a mass sell-off has not yet occurred, structural market changes are already visible to attentive observers. First, US stock indices are becoming more sensitive to changes in rates and macroeconomic signals. Fluctuations in long-term US government bond yields of similar magnitude now cause significantly larger stock price swings, especially in technology and growth sectors. This signals a weakening of the risk-bearing capacity of extreme investment funds.

Furthermore, the character of support for stock indices is changing. While arbitrage funds provided a “constant passive influx” of foreign capital, allowing indices to sustain more volatile internal dynamics, support now increasingly depends on “internal funds”—corporate buybacks and US fund placements. Sector rotation accelerates, but trend durations shorten, and this is not typical “capital outflow” but rather a change in the quality of capital. External liquidity is no longer expanding; the market can sustain itself only through its own mechanisms.

When numbers do not lie: why stock index resilience will not last long

At a deeper level, market volatility is reduced but extremely sensitive to shocks. The current state is a “protection” phase for arbitrage funds, where the market appears calm but is actually vulnerable. When any political or macroeconomic shock occurs, the reaction of stock indices sharply amplifies. This is characteristic of a system gradually unwinding leverage but not yet fully deactivating it.

According to the Maitong MSX research group, the real catastrophe of arbitrage operations will not be warned in advance. When it truly begins, the market will see a simultaneous combo: rapid yen appreciation during the day, a decline in US stock indices, widening credit spreads, uncontrollable volatility growth. We will already be in the aftermath phase, not in early warning.

Currently, the market is in a more subtle phase: arbitrage logic is questioned, but the system still holds. This is the most counterintuitive aspect of the modern global market: the real threat does not come from changes already occurred but from those accumulating but not yet triggered. The Japanese arbitrage operation, once an invisible driver of global risk assets, now resembles a slowing machine that has not yet stopped. US stock indices are moving precisely in this slowdown zone.

Data clearly indicate: as long as the rate differential between US and Japanese rates remains at 289 basis points, and speculative positions hold -44,000 net yen contracts short, US stock indices will not collapse due to yen fluctuations. However, stability depends on mathematics, not macroeconomic stories, and mathematics can change suddenly.