The mechanics are simple: when investors want more of an ETF than exists, authorized participants create new shares and the fund buys bitcoin to back them — an inflow. When investors sell more than the market absorbs, shares are redeemed and the fund sells coins — an outflow. The daily net of those two, published fund by fund each evening, is what the market shorthands as "flows."
Flows matter because they translate sentiment into forced, mechanical buying and selling of actual bitcoin. A $225 million outflow day isn't a survey result — it's coins hitting the market. That's why traders treat flow streaks as regime signals: an eight-week outflow streak defined the spring bear phase, a seven-day inflow streak underpinned
July's rally — until it snapped. Because ETF owners tend to be institutions managing rate risk, flows also explain why bitcoin has traded like a
risk asset rather than a haven in the ETF era.