Bitcoin Onchain Activity Surges Amid Coldcard Attack

The ongoing Coldcard attack has caused panic in the Bitcoin market, with onchain activity reaching its highest level of 2026. According to K33, a research and brokerage firm, the surge in coin movement during the past week resembles a pattern historically seen around local market tops and bottoms.

K33 estimates that at least 15 different attackers have exploited the vulnerability, resulting in about 1,596 BTC being stolen from roughly 7,300 addresses. The attack has also prompted some owners of hardware wallets to consider centralized custodians or multisignature setups.

Vetle Lunde, Head of Research at K33, stated that around 890,000 BTC has been moved over the past seven days, marking the highest level of active supply recorded this year. The acceleration came despite subdued price action, with bitcoin recording its narrowest 30-day high-to-low trading range since 2023 while realized volatility fell below that of the Nasdaq 100.

Lunde argued that such elevated onchain activity has repeatedly appeared near local market turning points, and that periods when seven-day active supply entered the top 10% of observations relative to its rolling 365-day history coincided with local tops and bottoms during previous market cycles.