Yen Trap Looms — Hedge Funds Overexposed

Japan’s former top currency official is warning that the yen is 20% undervalued — just as hedge funds place their biggest bet against it in nearly two decades.

Story Snapshot

Tatsuo Yamasaki, Japan’s former top currency official, says the yen is undervalued by up to 20% and should return to 130 yen per dollar.
Hedge funds now hold close to 138,000 net short contracts against the yen — the most bearish position since 2007.
The yen hit 162.83 per dollar in late June 2026, its weakest level since 1986, driven by a wide interest rate gap between Japan and the U.S.
Yamasaki warns that Japan’s Ministry of Finance can act without warning, putting short-sellers at serious risk of sudden losses.

A Veteran Official Sounds the Alarm

Tatsuo Yamasaki served as Japan’s Vice Minister of International Affairs at the Ministry of Finance — the country’s top currency diplomat. In a Bloomberg interview on July 6, 2026, he said the yen has drifted far from its true value. “This is no longer an issue of fundamentals — it’s distorted expectations,” he said. He believes the dollar-to-yen rate should fall back to around 130, compared to where it trades now near 162.

Yamasaki pointed to two forces that should push the yen higher. First, he expects Japan’s central bank — the Bank of Japan — to raise interest rates soon. Second, he thinks the U.S. Federal Reserve is unlikely to keep hiking rates. Both shifts would shrink the interest rate gap that has been driving investors away from the yen. “The Bank of Japan will undoubtedly raise interest rates next,” he said.

Hedge Funds Are Betting the Other Way

Despite Yamasaki’s warning, hedge funds are doing the opposite. Data from the U.S. Commodity Futures Trading Commission (CFTC) shows net short positions on the yen reached nearly 138,000 contracts as of June 30, 2026 — the most pessimistic reading since 2007. That means big money traders are betting the yen keeps falling. The dollar gained 2.45% against the yen in just the second quarter of 2026 alone.

The main fuel for this trade is a roughly 3% interest rate gap. Japan’s central bank holds its policy rate at 0.75%, while the U.S. Federal Reserve sits at 3.50–3.75%. Investors borrow cheaply in yen, then park that money in higher-yielding U.S. assets. This “carry trade” has crushed the yen for months. Japan’s government already spent a record 11.7 trillion yen — about $72–73 billion — trying to prop up the currency earlier in 2026, with little lasting effect.

The Hidden Risk for Short-Sellers

Yamasaki’s sharpest warning is about surprise. He says Japan’s Ministry of Finance still has the power to intervene in currency markets at any moment — and is more likely to use “smaller-scale, asymmetric covert operations” rather than big public moves. “Anyone shorting the yen knows they could be caught off guard by intervention at any time and forced to unwind their positions,” he said. That kind of sudden reversal could cause massive losses for hedge funds holding record short bets.

Hedge funds have turned extremely bearish on the Japanese yen $FXY, hitting the most negative positioning since 2007 as the currency nears a 40-year low, boosting the appeal of carry trades. #FX #Yen #Macro #CarryTrade #Japan

— ColumVox (@columvox) July 7, 2026

Markets have seen this movie before. In August 2024, a surprise shift in Bank of Japan policy triggered a violent carry trade unwind that shook global stocks in a single day. With short positions now even more extreme than they were then, the stakes are higher. Yamasaki put it plainly: “We are gradually approaching an inflection point.” Whether hedge funds are walking into a trap — or correctly reading a weak yen for years to come — is the trillion-dollar question hanging over currency markets right now.