The yen hoax: 30 trillion gone and the BOJ selling bonds

Thirty trillion yen in ten minutes and the Bank of Japan selling US Treasury bonds

Can you wipe out the Japanese stock market in the time it takes to brew a coffee? That's what a message circulating on social media claims: more than 30 trillion yen wiped off Japan's trading floor in ten minutes, with the Bank of Japan rushing to urgently sell all of its US Treasury bonds to stop the collapse. The text comes with mermaid emojis and the phrase "something very serious is happening." The first sensible response: we've seen this before.

A template that has been recycled since August 2024

The author of the message himself admits it is a recycled text. The yen-and-bonds refrain has been circulating since the Nikkei's crash in August 2024, and every time the carry trade unwinds a little, it reappears with new zeros. The pattern is always the same: an astronomical figure, an institution in panic, and an ending with ellipses.

The first objection is financial common sense. Japan holds around one trillion dollars in US Treasury bonds. Selling them "all urgently" is not a decision a central bank makes in ten minutes or announces in a tweet with emojis: it's a call to the Fed to open the swap line. And if that happens, it is communicated through official channels.

What would the Bank of Japan actually do in such a crash?

If 30 trillion yen really evaporated in ten minutes, the BOJ wouldn't be selling bonds: it would be firefighting with the yield curve control tap wide open, buying hand over fist. Selling is rookie stuff, not the firefighter's manual. The hoax's logic contradicts itself.

The conversation also brings up the idea that the Nikkei was artificially overinflated, and the immediate retort: the S&P 500 is even more so. The discussion drifts toward US debt and Europe's role as the next holder of the chain. "The printer is out of ink," one of the messages sums up, half joking, half serious.

The context: the ghost of the carry trade

The episode fits the pattern of scares the Japanese market has endured since the summer of 2024, when the unwinding of the carry trade —borrowing cheap in yen to buy assets in other currencies— triggered a global shock. Every resurgence of volatility revives the same apocalyptic narrative, with ever-growing figures and a different institution cast as the villain.

What the message doesn't say is what backs the figure. Thirty trillion yen is an amount that, in the context of the total market capitalization of Japan, would require explaining where the calculation comes from. Nobody does. The figure works as bait, not as data.

The final irony comes from the thread itself: if the BOJ were selling all of its American bonds in one go, the first party interested in knowing would be the US Treasury — and not exactly via a tweet. Meanwhile, the template will keep circulating. Fire up the printer and go to sleep.