Bitcoin ETFs notch best month of 2026 as BTC gains 25% in August

US-listed spot Bitcoin exchange-traded funds (ETFs) capped their best month of 2026 alongside Bitcoin’s biggest monthly gain since November 2024.Bitcoin ETFs attracted $3.52 billion in net inflows in August, their highest monthly total of 2026 and a sharp increase from just $172 million in inflows in July, according to SoSoValue data.Bitcoin (BTC) gained about 25% in August, its strongest monthly performance since a 37.29% rally in November 2024, according to CoinGlass.The August momentum quickly gave way to a weaker start to September, as ETF flows turned negative and Bitcoin briefly fell below $77,000.August cuts year-to-date outflows by 66% to $1.77BAugust’s $3.52 billion in Bitcoin ETF inflows cut year-to-date net outflows by roughly 66%, from $5.29 billion to $1.77 billion.The biggest monthly outflows came in June at $4.51 billion, followed by $2.43 billion in May and $1.61 billion in January, according to SoSoValue data.Monthly flows into US spot Bitcoin ETFs in 2026. Source: SoSoValueThe funds recorded net inflows on 16 of 21 trading days in August, including nine consecutive sessions from Aug. 17 through Aug. 27.Total net assets rose to $99.61 billion at the end of August from $76.29 billion at the end of July, an increase of about 31%. Monthly trading volume climbed nearly 49% to $58.63 billion from $39.37 billion.September starts with $236M in Bitcoin ETF outflowsUS spot Bitcoin ETFs started September with $236.46 million in net outflows on Tuesday, reversing the $216.70 million in net inflows recorded on Monday. The withdrawal marked the largest daily outflow since July 31, when the funds shed $265.37 million.The reversal came as Bitcoin briefly fell below $77,000 on Tuesday after trading above $80,000 in late August, according to CoinGecko.Ether and XRP ETFs remained in positive territory on Tuesday. Spot Ether (ETH) ETFs attracted around $11 million on Tuesday, while spot XRP (XRP) ETFs drew $14.4 million.August pushed Ether ETFs into positive territory for 2026, with $732 million in year-to-date net inflows after they ended July about $1.12 billion in the red.XRP ETFs reached $502 million in year-to-date net inflows, up about 46% from $343 million at the end of July.