September Flows and Market Reaction
September 2025 was a month of dramatic swings for ETFs. A torrent of cash flowed into both gold and Bitcoin funds, with large blocks of money arriving in single days, pausing, and then returning. BlackRock’s iShares Bitcoin Trust (IBIT) captured the largest share of these flows.
The activity was striking. On September 12th, spot Bitcoin ETFs absorbed $642 million. In the following days, from Wednesday to Monday, they pulled in an additional $2.2 billion. Another significant inflow of $223 million arrived on September 19th, with IBIT taking the lion’s share. This pattern of surges followed by drops defined the month, even as IBIT’s total holdings swelled past $86 billion. The month ended on a volatile note, with a single session on September 30th seeing an outflow of $363.2 million. MicroStrategy’s Michael Saylor aptly termed the phenomenon a “digital gold rush”.
This momentum was not confined to Bitcoin. Gold ETFs also reached fresh highs at several points during 2025. Deutsche Bank subsequently raised its 2026 gold forecast to $4,000 per ounce. Traders largely linked the simultaneous rush into both assets to increasing expectations of a Federal Reserve interest rate cut, which lowers the opportunity cost of holding non-yielding assets.
Implications
For portfolio managers, these September flows highlight four key features to consider.
The sheer size of IBIT means it controls a significant portion of readily tradable Bitcoin, potentially leaving less float available for the broader market.
There is a relative performance risk. If a risk-off mood intensifies, gold’s strong upward forecast could attract capital away from digital assets.
The sharp inflows and outflows demonstrate how leveraged money can amplify price swings, increasing volatility.
Both assets are now reacting to the same macro signal. Their prices are moving in step more frequently as they respond to shifts in the Fed policy outlook.
September’s activity has left treasuries and fund managers closely watching rebalancing dates and daily flow data. The open questions remain: will institutions continue their purchases, and how will new interest rate forecasts alter the calculus for holding gold and Bitcoin?
