Bitcoin has fallen 8 times in the past 13 Septembers. The U.S. stock market has also been plagued by the same issue since 1928.

Written by: Jose Antonio Lanz

Translated by: Blockchain in Plain Language

Bitcoin investors have lost money in 8 out of the last 13 Septembers. The average performance of the S&P 500 index in September since 1945 has been negative, and researchers at Yardeni have traced this pattern back to 1928.

Bitcoin is not the originator of this curse, but this digital asset has not escaped it either.

Cryptocurrency traders refer to it as "Red September," a cyclical market "nightmare" that resurfaces every year at this time. But this is not superstition; it is a stubborn data pattern that neither a 15-year-old asset nor a century-old stock index can escape.

What is the reason behind this?

Data Supporting the Curse

According to monthly return data tracked by CoinGlass, in the 13 complete years since 2013, Bitcoin has recorded losses in September 8 times, with a win rate of only 38.5%. The average return rate is -2.97%, with a median of -2.44%. Both of these figures are crucial: a negative median indicates that even in a "normal" September, there are losses, not just a few crashes dragging down the average.

During the same period, only June's performance came close to this dismal state, with an average decline of a relatively small 1.59%. The average returns for the other months on the calendar are all positive. In contrast, October is the most profitable month of the year, with an average return rate of up to 19.92% and a median of 14.71%, which is the origin of the "Uptober" market praised by the crypto community every year at this time.

The data for August is worth noting separately because it is deceptively high: while the average return rate for August appears to be 2.82%, the median return rate is -6.99%. In other words: the vast majority of Auguses are losing, with only a very few extreme bull years pulling the average into positive territory.

Not Limited to the Crypto Circle

Wall Street has recorded this phenomenon for a longer time and in more detail. Research from JPMorgan shows that since 1945, the average decline of the S&P 500 index in September is about 0.6%, being the only month with negative long-term average returns. If we extend the range to 1928, the data gets even worse, with an average decline close to 1.1% to 1.2%.

The causes are widely debated: mainstream views include that mutual funds typically end their fiscal year on October 31, and thus will concentrate on selling off losing positions in September for tax-loss harvesting; institutional traders returning from summer vacations will execute previously shelved risk-reduction trades; additionally, the mid-month Federal Reserve interest rate meetings often fall at points of maximum volatility.

None of these theories fully explain Bitcoin—Bitcoin has no fiscal year and no summer vacation, but it remains a financial investment asset.

This year also adds a layer of special variables: 2026 is an election year in the U.S. Since 1986, in the last 10 midterm election cycles, the average annual low in the U.S. stock market has often fallen on September 2, with the average retracement before the market stabilizes and rebounds being close to 17% of the previous peak. Given Bitcoin's current trading characteristics more closely resemble high Beta tech stocks rather than purely safe-haven assets, this correlation works both ways.

What Happened Last September

Last year (2025), "Red September" initially followed the usual patterns but then staged a dramatic turnaround. Bitcoin opened the month near $108,000, with the RSI indicator falling into the oversold zone around 38; even at the time, DYOR CEO Ben Kurland told Decrypt that "Red September" is more of a "myth than a mathematical law."

In the early stages of the market followed historical trends. By mid-month, a brutal week erased nearly $162 billion from the total market capitalization of cryptocurrencies, with Bitcoin dropping toward $112,000, hitting a low of $111,986 at one point. At that time, traders in the prediction market were betting on a nearly 60% chance of further downside.

However, Bitcoin then launched a strong rebound, significantly aided by ETF fund inflows. CryptoQuant viewed long-term holders transferring Tokens into ETFs as a bullish signal, and subsequently Bitcoin strongly rebounded, breaking through $114,000, ending the month with a gain of 5.16%, marking the third consecutive recorded green September.

Next, October Destroyed the Celebration

The rebound lasted only six days. On October 6, Bitcoin hit a historical high above $126,000, and the market's expectations for the "Uptober" rally seemed secure.

However, reality took a sharp turn. On October 10, President Donald Trump threatened to impose 100% tariffs on Chinese imports, making the crypto market the only trading venue to react. Within 24 hours, $19 billion in leveraged positions vanished, and 1.6 million traders were liquidated. Market maker Wintermute even stated that it completely paused trading because extreme volatility directly breached its internal risk control metrics.

On that day, Bitcoin plummeted from above $121,000 to below $102,000, with altcoins suffering even more; some Layer-2 Tokens evaporated 70% of their market value within hours. October ultimately ended down 3.69%, becoming the third October to decline since 2013. The market continued to deteriorate: November sank 17.67%, marking the bleakest November since 2018, and in June this year it dropped to around $59,300, a 21-month low. Cryptocurrency traders referred to this phase as the crypto winter.

Thus, last year was an unusual year: the market experienced "Green September" (Uptember) and "Red October" (Red October), which is completely contrary to historical norms.

The Current Market Dynamics of Bitcoin

Entering September 2026, Bitcoin is trading around $77,500. Prior to this, Bitcoin had just concluded August with an increase of nearly 25%—its best-performing August since 2021. The current upward momentum faces resistance below the resistance level of $81,455 to $82,538, with support range below at $73,670 to $75,157.

Since this spring, the macro environment has undergone drastic changes. Federal Reserve Chairman Kevin Warsh warned at the first Jackson Hole annual meeting that the year-on-year PCE price index is running at 3.7%, showing an accelerating trend over the past six months; the CME FedWatch tool indicates that the probability of an interest rate increase in September has now reached 68.2%. Meanwhile, the yield on 30-year U.S. Treasury bonds reached 5.28% at the end of August, the highest level since the 2008 financial crisis.

Gold has recently risen in sync with Bitcoin, revealing the true driving force of the current situation: it is not simply an increase in risk appetite, but rather an intensifying "currency devaluation hedging trade"—investors are betting that in the face of persistent inflation, the Federal Reserve will ultimately be forced to continue printing money. Additionally, the SEC’s "Regulation Crypto Assets" announced on August 18 has provided a rare regulatory cheer for the currently tense market sentiment.

The next critical test is on September 15 to 16, when the Federal Reserve will decide whether to initiate the first interest rate hike since the tightening cycle of 2022-2023—exactly that round of tightening caused Bitcoin to collapse about 65% and hit a deep low of $15,500 in November 2022.