Bitcoin (BTC) rallied more than 5% over the past 24 hours, climbing above $81,000 during US trading hours.

Key points:

• Bitcoin rose above $81,000 in US trading, gaining more than 5% over the past 24 hours.
• USD/JPY fell to 155.4 amid suspected Bank of Japan (BOJ) intervention, dragging the US Dollar Index (DXY) down to 99.
• Polymarket odds of a BOJ rate hold collapsed from 12% to 1%, with a 98% probability now priced in for a 25-basis-point hike on Sept. 18.

Weaker dollar drags crypto higher

At the time of writing, BTC stands at $81,000, near the highs seen during last month's surprise upside move.

The rally came as the Japanese yen (JPY) continued to strengthen amid a suspected central bank intervention, which Cointelegraph first reported on Wednesday. After dropping to 158.5 on Wednesday, the USD/JPY pair slid further to 155.4. That placed pressure on the DXY, which fell to 99. Historically, a weaker DXY has been positive for Bitcoin: because the cryptocurrency is priced in dollars globally, a softer greenback tends to make BTC comparatively cheaper for holders of other currencies.

Shares of Michael Saylor's Strategy (MSTR) joined the rally, rising 8.6% on Wednesday. The stock is up 70% from its lows in late June but remains down roughly 10% year-to-date. Strategy's perpetual preferred stock, STRC — frequently compared to a money market fund — is still trading below its $100 par value, stuck at $97.80 at the time of writing.

Related: Strategy turns 1,690 BTC into $108.6M STRC buyback

Analysts divided on impact of yen intervention

The latest suspected intervention to support the yen, together with the prospect of a Bank of Japan rate hike later this month, has revived fears of another carry-trade unwind. In a carry trade, investors borrow in low-yielding currencies such as the yen to fund positions in higher-yielding assets — a strategy in which Bitcoin and crypto-linked equities have at times been caught on the losing side when rapid yen strength forces leveraged positions to unwind.

"In the last 24 hours, USD/JPY has dropped almost 2.5%, which doesn't happen without any major intervention," The Macro Paper commented on X. "On top of that, BOJ is most likely expected to hike rates this month, with more rate hikes possible in Q4. This is the exact thing that happened in Q3 2024, when BOJ intervened and hiked rates together."

Polymarket's probabilities for a BOJ rate hold dropped from 12% to 1% on Wednesday, cementing expectations of a hike. The current market-implied probability of a 25-basis-point increase at the BOJ's Sept. 18 meeting stands at 98%.

Some observers view the currency intervention as liquidity-positive. Arthur Hayes, CIO of Maelstrom, has long argued that the Foreign and International Monetary Authorities' (FIMA) repo facility will provide Japan with dollar liquidity against Treasury collateral, easing global liquidity conditions. While no funds appear to have been drawn from the facility so far, Treasury Secretary Scott Bessent raised the prospect in late July. The divergence between these two readings — carry-trade unwind risk on one side, dollar liquidity support on the other — helps explain why analysts remain split on how the currency moves will ultimately flow through to crypto markets, with the BOJ's Sept. 18 decision now the key event to watch.