Spot Bitcoin ETFs pulled in $3.52 billion in August, up from just $172 million in July and their strongest month since October 2025, erasing roughly two thirds of the funds' 2026 deficit in a single stretch. Bitcoin gained about 25% over the same period, its best month since November 2024. The warning in the data is how quickly it turned, with September opening on a sharp reversal in flows before the month is two days old.