Bitcoin ETF Flows: $2.42 Billion by End of September

Net flows of U.S. spot bitcoin ETFs reached $2.73 billion from September 1 to 28, 2026, according to data from Farside Investors. August ended at $3.52 billion. However, September did not mirror August: $2.42 billion, or 88% of the total, came in six sessions from September 21 to 28. Cointribune reconstructed the two months session by session to illustrate this.

In Brief

• +$2.73 billion: net flows of bitcoin ETFs from September 1 to 28, over 19 sessions (Farside Investors, TFTC).
• Only +$313.5 million over the first 13 sessions, then +$2.42 billion over the next 6.
• +$3.52 billion in August, over 21 sessions, of which 16 were positive.

What Do Bitcoin ETF Flows Measure?

A spot bitcoin ETF is a publicly traded fund that holds bitcoin. When investors buy shares, the fund creates new ones and buys bitcoin. The net flow is the difference between these creations and redemptions, in dollars, for a session. Cointribune had tracked the moment when the flows of 2026 turned positive again.

The figures in this article sum the daily flows of all spot bitcoin ETFs listed in the United States. From September 10 to 28, they come from the table of Farside Investors. For August and early September, they come from TFTC, which compiles the same reported flows. The two series match within $0.1 million on common dates.

How Does September Compare to August?

August rose steadily. Sixteen sessions out of 21 were positive. The strongest, on August 20, brought in $606.3 million. The worst, on August 28, cost $201.8 million.

The flows of bitcoin ETFs in September followed a different trajectory. After thirteen sessions, the total did not exceed $313.5 million. On September 15, the funds lost $450.4 million in one session, the largest outflow of the two months. On that day, the U.S. Senate rejected the procedure that was supposed to advance the CLARITY Act by a vote of 49 to 50, according to CNBC. The data do not indicate whether the two events are related.

Then the curve turned upward. On September 21, the ETFs received $999 million, their best session of the two months. The following five sessions added $1.42 billion.

Sources: Farside Investors, TFTC, Cointribune calculations. Data consulted on September 29, 2026.

Bitcoin ETF Flows for the Whole of 2026

The balance for 2026 has turned positive again. By mid-July, bitcoin ETFs had recorded $5.8 billion in net outflows since January, according to data from SoSoValue. As of September 24, the annual total reached approximately $886.8 million in inflows, according to Decrypt, as reported by Yahoo Finance. Since their launch in January 2024, these funds have gathered $58 billion in net inflows, according to the same source.

What These Figures Do Not Say

Aggregators do not all publish the same amounts. For September 21, Farside counts $999 million, while Bitcoin Treasuries reports $1.41 billion. For September 15, the discrepancy ranges from −$450.4 million to −$198.1 million. The methods of collection and the times of reporting differ. Comparing figures from different sources thus skews the reading.

A net flow also does not indicate who is buying, nor why. It measures the demand for ETF shares in the United States, in dollars. It does not measure purchases on crypto platforms, nor demand outside the United States. To choose between an ETF and bitcoin held directly, our comparison between spot ETFs and bitcoin details the differences.

The flows of bitcoin ETFs in September ended at $2.65 billion, compared to $3.52 billion in August, according to Farside. The last session, on September 30, recorded $148.7 million in outflows, of which $125.6 million was for Fidelity's FBTC fund.