Spot ETF flows are the only daily public trace of institutional money in bitcoin. Here is how to read them and where they can mislead.

How a spot ETF works

A spot bitcoin ETF holds real bitcoin and issues shares that trade on a stock exchange. When demand for shares grows, authorised participants create new shares and the fund buys more bitcoin. When shares are redeemed, the fund sells coins. Inflows and outflows are the money that went through those creations and redemptions in a day.

US spot bitcoin ETFs have traded since January 2024. The largest by assets is BlackRock's IBIT, followed by funds from Fidelity and Grayscale.

When the data comes out

Funds disclose flows after the US market closes, so a trading day's numbers appear late that evening US time. There are no flows on weekends and US holidays, even though bitcoin keeps trading.

How to read flows

A single day means little: one large inflow can be a single client rebalancing. Look at streaks. Several days of large inflows mean steady demand from outside crypto exchanges, and that demand buys coins off the market. Sustained outflows work the other way.

Cumulative inflow is the sum of all flows since launch. It shows how much money actually came in, unlike fund assets, which rise and fall with the bitcoin price.

Why GBTC saw outflows

Grayscale Bitcoin Trust existed long before spot ETFs and converted into one in 2024 while keeping a 1.5% annual fee, several times more than competitors. Investors moved out of it into cheaper funds for months, which is why GBTC shows tens of billions in cumulative outflows. The total flow across all funds matters more than any single fund.

Where to track it

The bitcoin ETF flows page lists each fund's assets, daily flow, cumulative inflow, traded value and fee. There are also pages for Ethereum ETFs, Solana and XRP. Compare ETF flows with funding: a rally on ETF inflows with calm funding is driven by spot and usually holds better than one built on leverage.