Yen Surges Past 155:
Japan’s Record $90B Treasury Selloff

Up 4% in a week —
why did the 155 line give way so fast?

Trace the move. On 2 September we wrote “Yen Breaks 160 Again” when USD/JPY sat at 160.32, near the yen’s weakest point; on 5 September it bounced to 156.23, a 2.6% gain; today it has reached 153.26. From below 160, the yen has appreciated more than 4% in about a week, and the rate per 100 yen has climbed from 4.89 to 5.11.

The script we described last time is now playing out. Hedge-fund short positions in the yen sit at a 19-year high, measured in the hundreds of billions of dollars. JPMorgan warned that once USD/JPY breaks below 155, those shorts begin cutting losses — and cutting a short means buying yen. That buying pushes the yen higher, triggering more stops, in a self-reinforcing loop: the short squeeze. Currencies that fall for a long time can rebound violently.

Why 155 matters is not just psychology — it is the level JPMorgan identified as the short-covering trigger. The yen has now also broken above the highs set after the US–Japan joint intervention in early August. In other words, even the level that “official action” defended has fallen: the market no longer believes intervention will reverse the trend.

$90 billion of Treasuries —
the real money behind a record intervention

What sets this round apart from the early-August intervention is where the money came from. The market reportedly found that Japan sold nearly US$90 billion of US Treasuries to steady the yen — one of the largest intervention funding operations on record. Sell Treasuries, raise dollars, buy yen in the market: every step is real money.

Why so big? Because the opponent this time is the entire carry-trade market. For years, global money has borrowed yen at near-zero rates to buy US Treasuries, Japanese equities and emerging-market assets, pocketing the rate gap — positions that together run into the hundreds of billions of dollars. To make them retreat, a small intervention barely moves the needle; when you act, you have to act hard.

But selling Treasuries has its own ripple. Japan is one of the largest foreign holders of US government debt; large-scale selling adds supply and puts upward pressure on Treasury yields. In other words, Japan props up the yen by selling US bonds — and the bill for that trade is higher US bond yields. How that ledger balances out over time, the market is still calculating.

A stronger yen:
three ways it hits Hong Kong wallets

This story touches Hong Kong wallets in three places.

First, travel to Japan. In early September the rate was still 4.89; in under a week it has reached 5.11 — the same trip now costs more than 4% extra in Hong Kong dollars. If you are planning an autumn or Christmas trip, the cost is locked in near the highs; if you are waiting for a pullback before converting, remember: the faster the yen rises, the wider the gap between bank telegraphic rates and cash rates. Compare the actual rate you will get before converting.

Second, yen deposits and yen holdings. Those who opened a yen deposit or built a yen stash near the lows are now earning interest plus currency gains — the winners. But those rushing in only now that the yen has bounced should do the math: deposit rates of one or two percent can be wiped out by a single pullback in the exchange rate. The mathematics of foreign-currency investing never changes — no matter how high the interest rate, the exchange rate can erase it.

Third, carry-trade unwinding — and this is the biggest risk. As hundreds of billions of dollars of shorts begin to cover, it is not just the yen that moves. Positions that borrowed yen to buy US Treasuries, Japanese equities and emerging markets must sell assets to repay the yen. When an unwind begins, global risk assets come under pressure together — Hong Kong stocks fell alongside them in the early-August episode. We are only at the start; how many positions still need to be closed, nobody knows.

The line is broken —
what should retail investors do now?

To be blunt: the most dangerous moment has passed — the worst hurt are those who were still shorting the yen near 160, standing on the same side as the billion-dollar shorts. But for ordinary investors, a different temptation has arrived: the yen looks so strong now that it is easy to chase it, to open a yen deposit or buy the currency on the way up.

Practically, three principles. One: if you have a genuine need — travel, study, spending in Japan — do not skip converting just because the yen is up 4%, and do not try to catch the perfect level in one go; convert in tranches to average your cost, which always beats betting on a single day. Two: if you have no genuine need and are purely speculating on the exchange rate, recognise what you are buying: you are catching the currency at a 7-month high, paying for the expectation that shorts keep covering. That expectation is already nine-tenths priced in — you are chasing the last tenth of the move, while the downside can be brutal. Three: never use leverage to bet on “whether it goes higher” — the signal that a squeeze is ending is often the moment retail piles in.

Want to watch the rate before you decide? FinKit’s currency converter shows live rates across 17 currencies and compares bank telegraphic transfer versus cash rates — at least you will know the level you are buying at, instead of guessing.

Read the previous instalments → Yen Rebounds to 156: JPMorgan Warns of a $100B Short Squeeze and Yen Breaks 160 Again: Intervention Fades, BOJ Hike Looms