Bitcoin and Ethereum in 2025: price swings, ETF flows, and the 2026 outlook

In 2025, Bitcoin and Ethereum saw sharp moves—Bitcoin fell by March, rebounded mid-year, set new highs in October, and pulled back in November; Ethereum rallied late summer but faded in Q4. Bitcoin is down around 6%, Ethereum nearly 12%, with altcoins off more than 40%. ETFs mattered more for Bitcoin, while Ethereum's demand proved fragile.