JPMorgan Warns of Yen 'Selling Cascade' if Dollar Breaks Below 155

The Japanese yen surged nearly 2% against the U.S. dollar on Thursday, its largest single-day advance since a joint U.S.-Japan intervention in late July. The sharp rally has brought a key technical level into focus, with strategists warning of further, more rapid appreciation if bearish bets are forced to unwind.

JPMorgan Warns of 'Cascade' Sell-Off

Strategists at JPMorgan Chase & Co. are cautioning that a move below the 155 mark in the dollar-yen pair could trigger a rapid liquidation of massive short positions against the yen. In a report, strategists including Junya Tanase noted there are an estimated ¥16 trillion to ¥17 trillion (approx. $102.6 billion) in outstanding bearish yen positions.

Should the dollar fall below 155 against the yen, the report states, “we cannot rule out the risk that selling begets more selling, driving the yen’s appreciation beyond expectations.” JPMorgan estimates that a complete unwinding of these short positions could theoretically push the USD/JPY pair down into the 142 to 146 range.

However, the bank also noted that recent market expectations for a portfolio shift by Japan's government pension fund and for faster Bank of Japan rate hikes appear "somewhat excessive." As a result, they see a low probability of the pair breaking significantly outside their assumed 155-165 range in the near term.

Catalysts Behind the Yen's Rebound

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The yen's sudden strength was driven by a confluence of factors that prompted investors to cover their short positions.

• BOJ Hawkishness: Comments from Bank of Japan board member Hajime Takata suggesting that consecutive interest rate hikes were possible fueled speculation of a more aggressive tightening cycle. Swap markets are now almost fully pricing in a 25-basis-point hike at the BOJ's September 18 meeting.
• Pension Fund Speculation: Market rumors suggested Japan's Government Pension Investment Fund (GPIF), the world's largest, might increase its allocation target for domestic bonds, which would boost demand for the yen.
• Weaker U.S. Dollar: Dovish remarks on inflation from U.S. Federal Reserve Governor Christopher Waller weakened the dollar broadly. The move narrowed the interest rate differential between the U.S. and Japan, making the yen more attractive.

Intervention Watch and Policy Focus

The rally follows a period of renewed weakness for the yen, which saw the dollar climb back above 160 earlier this week, testing the resolve of Japanese authorities. Japan spent a record $96.4 billion over the past month to support its currency following the late-July joint intervention.

Japanese officials have adopted a more forceful tone. The country's top currency diplomat, Atsushi Mimura, vowed to "continue to fight in the foreign exchange market," a stronger stance than his recent remarks. With Japan's "Silver Week" holiday approaching, traders are on high alert for a potential intervention, as authorities have previously acted during periods of thinner holiday liquidity.