Author: David, TechFlow Deep Tide
On December 15, Bitcoin fell from $90,000 to $85,616, a single-day drop of over 5%.
There were no major negative events or scandals on this day, and on-chain data showed no abnormal selling pressure. If you only looked at crypto news, it was hard to find a "plausible" reason.
On the same day, gold was quoted at $4,323 per ounce, down only $1 from the previous day.
One fell 5%, the other barely moved.
If Bitcoin is truly "digital gold," a tool to hedge against inflation and fiat currency devaluation, its performance in the face of risk events should be more like gold's. But this time, its movement clearly resembled that of high-beta tech stocks in the Nasdaq.
What is driving this round of decline? The answer may lie in Tokyo.
The Butterfly Effect from Tokyo
On December 19, the Bank of Japan (BOJ) will hold its monetary policy meeting. The expectation is that it will raise interest rates by 25 basis points, increasing the policy rate from 0.5% to 0.75%.
0.75% may not sound high, but this is Japan's highest interest rate in nearly 30 years. On prediction markets like Polymarket, traders have priced the probability of this rate hike at 98%.
Why would a decision by a central bank far away in Tokyo cause Bitcoin to drop 5% within 48 hours?
It starts with something called the "yen carry trade."
The logic is actually quite simple:
Japanese interest rates have long been near zero or even negative, making it almost free to borrow yen. As a result, global hedge funds, asset management institutions, and trading desks borrow large amounts of yen, convert it to US dollars, and then buy higher-yielding assets, such as US Treasury bonds, US stocks, or even cryptocurrencies.
As long as the return on these assets is higher than the cost of borrowing yen, the interest rate differential is profit.
This strategy has existed for decades and is so large its size is difficult to measure precisely. Conservative estimates are in the hundreds of billions of dollars; some analysts believe it could be as high as trillions when including derivative exposures.
Additionally, Japan holds a special status:
It is the largest foreign holder of US Treasury bonds, holding $1.18 trillion in US debt.
This means changes in Japanese fund flows directly impact the world's most important bond market, which in turn affects the pricing of all risk assets.
Now, as the Bank of Japan decides to raise interest rates, the underlying logic of this game is being challenged.
First, the cost of borrowing yen rises, narrowing the carry trade arbitrage space; more troublesome is that rate hike expectations will push the yen to appreciate, and these institutions originally borrowed yen and converted it to dollars to invest.
Now, to repay the loans, they must sell dollar-denominated assets and buy back yen. The more the yen appreciates, the more assets they need to sell.
This "forced selling" doesn't pick a time or choose assets. Whatever has the best liquidity and is easiest to liquidate gets sold first.
Therefore, it's easy to see why Bitcoin, traded 24/7 with no price limits and relatively shallower market depth compared to stocks, is often the first to be sold off.
Looking back at the timeline of the Bank of Japan's previous rate hikes, this speculation is also somewhat corroborated by the data:
The most recent instance was on July 31, 2024. After the BOJ announced a rate hike to 0.25%, the yen appreciated against the dollar from 160 to below 140. BTC fell from $65,000 to $50,000 within the following week, a drop of about 23%, wiping $60 billion in market capitalization from the entire crypto market.
According to statistics from multiple on-chain analysts, BTC experienced drawdowns of over 20% following the past three Bank of Japan rate hikes.
The specific start and end points and time windows for these numbers vary, but the direction is highly consistent:
Every time Japan tightens monetary policy, BTC is a major casualty.
Therefore, the author believes that what happened on December 15 was essentially the market "front-running." Even before the decision on the 19th was announced, funds had already begun to withdraw early.
On that day, US BTC ETFs saw a net outflow of $357 million, the largest single-day outflow in nearly two weeks; over $600 million in leveraged long positions were liquidated in the crypto market within 24 hours.
This likely wasn't panic selling by retail investors, but rather the chain reaction of carry trade unwinding.
Is Bitcoin Still Digital Gold?
The previous section explained the mechanism of the yen carry trade, but one question remains unanswered:
Why is BTC always the first to be sold and hurt?
A common explanation is that BTC has "good liquidity and 24/7 trading"—this is true, but it's not sufficient.
The real reason is that BTC has been repriced over the past two years: it is no longer an "alternative asset" independent of traditional finance, but has been welded into Wall Street's risk exposure.
In January of last year, the US SEC approved spot Bitcoin ETFs. This was a milestone the crypto industry had waited a decade for, allowing trillion-dollar asset management giants like BlackRock and Fidelity to compliantly include BTC in their clients' investment portfolios.
The money did come. But along with it came an identity shift: the holders of BTC changed.
Previously, BTC was bought by crypto-native players, retail investors, and some aggressive family offices.
Now, BTC is bought by pension funds, hedge funds, and asset allocation models. These institutions also hold US stocks, US bonds, and gold, and manage "risk budgets."
When the overall portfolio needs to reduce risk, they don't just sell BTC or just sell equities; they reduce positions proportionally across the board.
Data shows this binding relationship.
In early 2025, the 30-day rolling correlation between BTC and the Nasdaq 100 index reached 0.80, its highest level since 2022. In contrast, before 2020, this correlation typically hovered between -0.2 and 0.2, essentially uncorrelated.
More notably, this correlation significantly increases during periods of market stress.
The March 2020 pandemic crash, the Fed's aggressive rate hikes in 2022, tariff concerns in early 2025... every time risk-off sentiment heats up, the联动 between BTC and US stocks tightens.
Institutions in panic don't distinguish between "this is a crypto asset" and "this is a tech stock"; they only see one label: risk exposure.
This leads to an awkward question: is the digital gold narrative still valid?
If you extend the timeline, gold has risen over 60% year-to-date in 2025, its best year since 1979; BTC has drawn down over 30% from its high during the same period.
Two assets both hailed as hedges against inflation and fiat devaluation have charted completely opposite curves in the same macro environment.
This isn't to say BTC's long-term value is in question; its five-year compound annual growth rate still far exceeds that of the S&P 500 and Nasdaq.
But at this current stage, its short-term pricing logic has changed: it is a high-volatility, high-beta risk asset, not a safe haven.
Understanding this is key to understanding why a mere 25 basis point hike by the Bank of Japan could cause BTC to drop thousands of dollars in 48 hours.
It's not because Japanese investors are selling BTC, but because when global liquidity tightens, institutions reduce all risk exposures using the same logic, and BTC happens to be the most volatile and easiest-to-liquidate link in that chain.
What Will Happen on December 19?
At the time of writing this article, there are two days left until the Bank of Japan's monetary policy meeting.
The market has already treated the rate hike as a foregone conclusion. Japan's 10-year government bond yield has risen to 1.95%, an 18-year high. In other words, the bond market has already priced in the tightening expectations.
If the rate hike is fully expected, will there still be an impact on the 19th?
Historical experience says: yes, but the intensity depends on the wording.
The impact of a central bank decision is never just about the number itself, but the signal it sends. The same 25 basis point hike will be met with relief if BOJ Governor Ueda says in the press conference, "We will carefully assess future moves based on data";
If he says, "Inflation pressures persist, and further tightening cannot be ruled out," that could be the starting point for another wave of selling.
Japan's current inflation rate is around 3%, above the BOJ's 2% target. The market's fear is not this single rate hike, but whether Japan is entering a sustained tightening cycle.
If the answer is yes, the unwinding of the yen carry trade is not a one-time event, but a process that could last for months.
However, some analysts believe this time might be different.
First, speculative positioning on the yen has shifted from net short to net long. The sharp drop in July 2024 was partly because the market was caught off guard, with large amounts of funds still shorting the yen. Now the positioning direction has reversed, limiting the room for unexpected appreciation.
Second, Japanese government bond yields have been rising for most of the year, from 1.1% at the start of the year to nearly 2% now. In a sense, the market has "already raised rates itself," and the Bank of Japan is merely acknowledging an established fact.
Third, the Federal Reserve just cut rates by 25 basis points; the general direction of global liquidity is easing. Japan is tightening against the trend, but if US dollar liquidity is sufficiently abundant, it might partially offset the pressure from the yen side.
These factors don't guarantee that BTC won't fall, but they might mean the decline won't be as extreme as in prior instances.
Looking at the performance following previous BOJ rate hikes, BTC typically bottomed out within one to two weeks after the decision, then entered a period of consolidation or rebound. If this pattern still holds, the window from late December to early January might see the highest volatility, but it could also present opportunities to position after mispriced sell-offs.
Being Accepted, Being Influenced
Stringing the previous sections together, the logical chain is actually quite clear:
Bank of Japan rate hike → Unwinding of yen carry trade → Tightening of global liquidity → Institutions reduce positions according to risk budget → BTC is sold first as a high-beta asset.
In this chain, BTC didn't do anything wrong.
It was simply placed in a position it cannot control: the end of the global macro transmission chain.
You might find it hard to accept, but this is the new normal in the ETF era.
Before 2024, BTC's price movements were mainly driven by crypto-native factors: halving cycles, on-chain data, exchange dynamics, regulatory news. Back then, its correlation with US stocks and bonds was low, and it somewhat resembled an "independent asset class."
After 2024, Wall Street arrived.
BTC was placed into the same risk management framework as stocks and bonds. Its holder structure changed, and its pricing logic followed suit.
BTC's market cap surged, rising from a few hundred billion dollars to $1.7 trillion. But it also brought a side effect: BTC's immunity to macro events disappeared.
A single sentence from the Fed or a decision by the Bank of Japan can cause it to fluctuate over 5% in a matter of hours.
If you believed in the "digital gold" narrative, believing it could provide shelter in turbulent times, the price action in 2025 is somewhat disappointing. At least at this current stage, the market is not pricing it as a safe-haven asset.
Perhaps this is just a phase of misalignment. Maybe institutionalization is still in its early stages, and once allocation ratios stabilize, BTC will rediscover its own rhythm. Perhaps the next halving cycle will once again prove the dominance of crypto-native factors...
But until then, if you hold BTC, you need to accept a reality:
You are also holding an exposure to global liquidity. What happens in a conference room in Tokyo may determine your account balance next week more than any on-chain metric.
This is the cost of institutionalization. As for whether it's worth it, everyone has their own answer.
