Bitcoin price usually stalls in September. That sell‑off has already begun: after topping $124,000 on Aug. 13, Bitcoin fell about 13% by month’s end.
Since 2013 it has closed lower on 8 of 12 Septembers, averaging roughly — 3.8% for the month. This seasonal dip mirrors equities. The S&P 500 averages about –1.2% in September.
Bitcoin Price Seasonal September Weakness
September has long been Bitcoin’s weakest month. CoinGlass data show the average September return is about –3.77% since 2013 – by far the lowest of any month.
In Bitcoin’s early days, price data was fragmented and not consistently recorded. The cryptocurrency crossed $1,000 for the first time in 2013.
It captured mainstream media attention and leading to more systematic tracking. That same year, CoinMarketCap launched, with CoinGecko following in 2014 as another key aggregator.
In eight of the last 12 years (2013–2024) Bitcoin price fell during September. Traders even dub this the “September effect,” as markets often sell off after late-summer rallies.
From 2013 to 2016, Bitcoin price’s September track record was balanced, posting gains in two years and losses in two.
That trend shifted in 2017 amid the surge of the initial coin offering (ICO) boom, when Bitcoin climbed back above $1,000 and quickly broke past $2,000.
The wave of speculation drew regulatory pushback: on Sept. 4, China’s central bank banned ICOs, triggering the first of six straight losing Septembers.
Factors In Play
Later that month, on Sept. 29, South Korea introduced its own ICO ban, while regulators in other countries issued cautionary notices.
That bearish stretch finally ended. Bitcoin price posted gains in September 2023 and 2024, including a record +7.29% jump in Sept. 2024.
Institutional catalysts helped flip the script. For example, an Aug. 29, 2023 appeals‑court ruling on Grayscale’s spot‑ETF bid revived hopes of U.S. ETFs, lifting Bitcoin roughly 4% that month.
In January 2024, several U.S. spot Bitcoin ETFs began trading, opening a new institutional demand channel that supported the late‑year rally.
Investors are focused on the Fed’s Sept. 16–17, 2025 meeting. Futures imply about a 95% chance of a 25‑bp rate cut that week.
Fed Governor Christopher Waller has said he “would support a 25 basis point cut” in September and expects further cuts over the next 3–6 months.
Chair Jerome Powell’s late‑Aug. Jackson Hole’s speech also struck a dovish tone, warning that a “shifting balance of risks” might warrant easing policy.
For context, the Fed kicked off an easing cycle in 2024 – on Sept. 18, 2024 it cut rates by 50 bps to 4.75%–5.00%. If a cut comes in mid‑September, it would extend last year’s dovish turn.
New flows may blunt September’s seasonal drag. U.S. spot Bitcoin ETFs, launched Jan 2024, have quickly amassed large portfolios. By mid-2025 they were trading billions of dollars each day and “continue to post billions in turnover.”
Some public companies have even added Bitcoin to their treasuries in 2025. Taken together, these ETF inflows and related capital shifts have given Bitcoin extra support through late summer, partially offsetting the usual September weakness.
October “Uptober” Rally
History suggests any late‑September dip often reverses in October. CoinGlass data confirm Bitcoin price gained in October six years in a row and has seen only two losing Octobers on record.
October now ranks as Bitcoin’s second‑strongest month (after November). In past cycles the so‑called “Uptober” rally frequently recovered September’s losses, hinting that this seasonal pattern could play out again in 2025.
