Bitcoin has closed lower in eight of the last 13 Septembers, with an average loss of 2.97%, making it the worst month of the year by both average and median return.

September 2025 broke the streak with a 5.16% gain—Bitcoin's third consecutive green close—only for October to turn negative for the first time since 2018, days before a tariff threat from President Donald Trump triggered $19 billion in liquidations.

As September 2026 opens, Bitcoin trades around $77,500 following a near-25% jump in August, while the Federal Reserve weighs its first rate hike since 2023 and a midterm election year adds its own seasonal drag on top.

Bitcoin investors have lost money in eight of the last 13 Septembers. The S&P 500 has averaged a September loss since 1945, and researchers at Yardeni have traced the pattern back to 1928. Bitcoin did not invent this curse—but the digital asset has joined it.

Crypto traders call it "Red September," a cyclical market boogeyman that resurfaces every year around this time. It is not superstition, however. It is a data pattern stubborn enough that both a fifteen-year-old asset and a hundred-year-old stock index cannot shake it. Worth noting, though: 13 observations is a small sample by statistical standards, and even the S&P's nearly century-long September record has produced long stretches of green Septembers in between. Seasonality describes what has happened, not what must happen—which is exactly why some strategists dismiss the whole framing as pattern-matching on noisy data.

The math behind the curse

According to monthly return data tracked by CoinGlass, Bitcoin has closed September lower in eight of 13 completed years since 2013—a 38.5% win rate. The average return is negative 2.97% and the median is negative 2.44%. Both numbers matter: a negative median means even a "normal" September loses money, rather than a couple of catastrophic years dragging down the average.

Only June comes close, averaging a smaller 1.59% loss over the same period. Every other month on the calendar is positive on average. October, the best month by a wide margin, has returned 19.92% on average with a 14.71% median—the "Uptober" reputation that crypto Twitter celebrates each time it arrives.

August deserves a footnote, because its headline number is misleading. The average return is a respectable positive 2.82%, but the median is negative 6.99%. In other words, most Augusts lose money, and only the exceptional years among them push the average into positive territory.

It's not just crypto

Wall Street's version of this pattern is older and better documented. According to Chase's own market research, the S&P 500 has averaged roughly a 0.6% decline in September since 1945—the only month with a negative long-run average. Extending the data back to 1928 makes the number worse, closer to a 1.1%–1.2% average loss.

No one agrees on the cause. The leading theories: mutual funds close their fiscal year on October 31 and dump losing positions in September to harvest tax losses; institutional desks return from summer break and execute deferred de-risking all at once; and the Fed's mid-month meeting tends to land in the middle of the chop.

None of those explanations apply to Bitcoin, which has no fiscal year and takes no summer vacation, yet remains a financial investment all the same. What Bitcoin does share with equities is a growing institutional holder base: spot Bitcoin ETFs, approved in the U.S. in January 2024, tethered the asset more tightly to the flows, hedging behavior, and risk sentiment of traditional finance—giving old Wall Street calendar effects new channels to leak into crypto prices.

This year adds an extra layer. 2026 is a midterm election year, and across the last 10 midterm cycles since 1986, the average U.S. stock market low has landed on September 2, with drawdowns averaging nearly 17% from the prior high before markets recover. Bitcoin now trades more like a high-beta tech stock than a hedge, so that correlation cuts both ways.

What happened last September

Last year's Red September followed the script, then flipped it. Bitcoin opened the month trading near $108,000 with its RSI reading oversold around 38, and DYOR CEO Ben Kurland told Decrypt that the idea of Red September is "more myth than math."

Math won the early rounds. By mid-month, a brutal week had wiped roughly $162 billion off crypto's total market cap and pushed Bitcoin down toward $112,000, briefly touching an intraday low near $111,986. On Myriad, the prediction market built by Decrypt's parent company Dastan, traders were pricing nearly 60% odds of another red day at the bottom.

Bitcoin clawed its way back regardless. ETF inflows played a role: CryptoQuant flagged long-term holders rotating coins into ETFs as a bullish signal, and Bitcoin rallied above $114,000 to close the month up 5.16%—the third consecutive green September on record.

Then October wrecked the party

The redemption arc lasted six days. Bitcoin hit a fresh all-time high above $126,000 on October 6, and the "Uptober" trade looked bulletproof once again.

It was not. On October 10, President Donald Trump threatened 100% tariffs on Chinese imports, and crypto was the only market open to react. Within 24 hours, $19 billion in margin positions were wiped out, 1.6 million traders were liquidated, and market maker Wintermute told Decrypt it stopped trading entirely because the move broke its internal risk rules. That kind of cascade is how leveraged crypto works: when prices fall far enough, exchanges force-close collateralized positions, and those sales push prices lower still, triggering the next wave.

Bitcoin fell from above $121,000 to briefly below $102,000 that day, dragging altcoins down even harder—some layer-2 tokens lost 70% within hours. October closed down 3.69%, only the third red October since 2013, and the damage compounded from there: November finished down 17.67%, Bitcoin's worst November since 2018, on the way to a 21-month low near $59,300 by this past June. Crypto traders have taken to calling that stretch the crypto winter.

Last year, in short, was atypical: Uptober turned into Red October, which is not how the market usually behaves.

Bitcoin's setup this time

Bitcoin is trading around $77,500 as September opens, down slightly on the day after closing out a nearly 25% August—its best August since 2021. The rally has stalled just under resistance between $81,455 and $82,538, with support sitting in the $73,670 to $75,157 zone below.

The macro picture has shifted sharply since spring. Fed Chair Kevin Warsh used his first Jackson Hole speech to flag that the PCE price index is running at 3.7% annually and accelerating on a six-month basis, and CME's FedWatch tool now puts the odds of a September rate hike at 68.2%. The 30-year Treasury yield touched 5.28% in late August, a level last seen before the 2008 financial crisis. Higher rates generally pressure risk assets by making yields on safe holdings like Treasuries more competitive—an environment in which Bitcoin has historically struggled to rally.

Gold has been rallying alongside Bitcoin, which points to what is actually driving the market: not risk appetite so much as a growing debasement trade, with investors hedging against a Fed that might be forced to keep printing while inflation refuses to cooperate. The SEC's proposed Regulation Crypto Assets rule, published August 18, adds a rare regulatory tailwind to an otherwise jumpy setup.

The next hard date is September 15–16, when the Fed decides whether to raise rates for the first time since its 2022–2023 tightening cycle—a stretch that dragged Bitcoin down roughly 65% to a $15,500 low in November 2022.

Disclaimer: The views and opinions expressed by the author are for informational purposes only and do not constitute financial, investment, or other advice.