Bitcoin (BTC) ended September with a 6.33% increase, breaking the trend where September has typically closed in the red since 2013. However, demand at the beginning of October is noted to be declining, and the number of buyers is decreasing.
Since 2013, September has traditionally brought Bitcoin an average loss of 2.41%, according to Coinglass. However, over the past four years—from 2023 to 2026—the month ended with growth. During the latest increase, Bitcoin also showed the best performance compared to traditional assets. Analysts at Santiment noted that gold fell by more than 6% in September, and the S&P 500 showed a moderate decline. Additionally, CryptoQuant interprets September's results as the start of a new bull market. The recent close above the 365-day moving average confirms this change, and the Bull Score index is 90 out of 100. Historical October data also supports this view: Bitcoin ended 10 of the last 13 Octobers with growth, with a median increase of 12.73%. However, flow data shows that the number of buyers is decreasing.
In September, U.S. spot Bitcoin ETFs attracted $998.95 million on September 21—the largest inflow in nearly a year. However, in the following sessions, inflows significantly decreased, dropping to $31.07 million by September 28. On September 30, the funds showed an outflow of $148.69 million, with none of the 12 ETFs recording an inflow.
The decline in ETF inflows reflects a broader drop in demand. CryptoQuant estimates that apparent spot demand decreased by 170,000 BTC over 30 days. Moreover, the growth in futures demand slowed from 164,000 BTC on September 14 to 16,000 BTC. Trading volume also remained low: Glassnode reports that the total volume of spot and ETF trades is about $6.4 billion per day, which is at the lower end of the range since launch.
As new demand cools, existing holders have stepped up sales on the rise. On September 22, holders realized a profit of 25,700 BTC—the largest one-day figure of 2026. The share of long-term holders (more than 155 days) in the total realized profit increased from 34% to 55% for the week ending September 29. CryptoQuant also noted that traders' unrealized margin reached 33%—the highest since December 2024. "Historically stretched margins preceded sales and downward pressure on price," the report states. Meanwhile, Glassnode noted that overall profit realization remains below the levels observed at the peaks of 2024 and 2025.
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