Bitcoin rallies after BOJ’s 1.25% hike, but the real yen-carry test starts next week

The Bank of Japan announced a policy-rate increase to about 1.25% on Sept. 18, yet the visible Bitcoin and currency response showed limited signs of a disorderly yen-carry unwind.

The BOJ voted 7-2 to lift its target for the uncollateralized overnight call rate by 25 basis points, from about 1% to about 1.25%. The new target and related facility rates take effect Sept. 24, so the decision changed the policy path before it changed the official operating rates.

That separates a scheduled funding-cost change from the market’s reaction to the announcement. Positions can adjust before implementation, and the BOJ’s next signal could matter as much as Sept. 24 because the bank tied further increases to its economic and inflation outlook instead of a fixed timetable.

That distinction matters for yen-funded trades. Investors can borrow yen to buy higher-returning assets elsewhere. A higher Japanese rate reduces the trade’s interest-rate advantage. If the yen appreciates, overseas borrowers must buy a more expensive currency to repay yen-denominated debt, increasing repayment costs in their home currency. Both forces can pressure leveraged risk positions, including crypto exposure.

The available evidence leaves the amount of Bitcoin exposure financed in yen unquantified. Coinbase Institutional’s review of the 2024 carry episode identified several simultaneous catalysts, including weak US economic data and pressure on technology stocks. Yen funding is one transmission channel among several that can shape crypto moves.