Bank of Japan Governor Ueda said the board would "decide on policy with upside price risks in mind" at its September 17-18 meeting, markets priced roughly 94% odds of a hike, and the yen reversed from 160.1 to briefly touch the low-158s on intervention alert.
Japan is the largest foreign holder of Treasuries, and Japanese institutions hold them hedged; the hedge cost is set by the short-rate gap. A BOJ hike narrows that gap from the Japanese side at the same moment a 3% JGB offers a domestic alternative for the first time in a generation, so the marginal Japanese buyer of the US long end faces a lower hedged yield and a better home substitute simultaneously. Ueda hinting is the market pricing the flow before it happens; the yen reversal is the first visible leg of that repricing.
Scenarios 2
The hike is delivered, the yen firms, and Japanese repatriation shows up as a persistent bid for JGBs and a persistent offer in Treasuries — the "global selloff" stops being a shared term premium and becomes a flow-of-funds story with a named seller.
Checkable on two lagged series this map already collects: Treasury TIC's Japan line (two-month lag) and the MOF weekly securities-flow data. If Japanese net Treasury purchases turn negative in the September-October prints while the JGB curve bull-flattens, the mechanism is running; if TIC shows continued buying, the yen move was positioning, not repatriation.
Precedent — The 2022 episode: the BOJ's December yield-curve-control widening sent the 10-year JGB through its band and Japanese life insurers cut hedged Treasury holdings through 2023 — the largest foreign seller that year — while US term premium rose independently of Fed policy.
Ueda is talking the yen up to avoid intervening, the hike is small or deferred to October, and the transmission stalls — the low-158 print was a squeeze on short-yen positioning, not a regime change, and Treasuries keep trading on US supply and oil.
The tell is the size and the language on 09-18: a 25bp move with "gradual" guidance and no balance-sheet change leaves the hedge-cost gap wide enough that US paper still wins on a hedged basis. Bessent's public pressure for "also rate hikes" cuts the other way and is itself a novelty worth weighting.
Precedent — The 2024 sequence: the BOJ's March exit from negative rates and the July hike produced a violent yen squeeze and the August 5 global equity unwind, then faded within weeks as the carry trade rebuilt — the currency moved far more than the cross-border bond flow did.
Context
capital-context.yaml's rate_regime reading is entirely US-domestic and its own comment block twice deferred a BOJ/JGB leg as a /week-scale gap. Two consecutive days have now produced real misses on exactly that leg, one of them with 108 buffer hits; the standing snapshot needs the leg written in, not deferred again.
This is generated reasoning, not a sourced fact — the mechanism and scenarios above are the model's read on what this item could mean for capital flows, tagged with its own confidence rather than stated as settled. Back to Global Capital.