Bitcoin's Mempool Is the Busiest Since February 2025

Bitcoin's mempool, the queue of transactions broadcast to the network but not yet written into a block, held 89,031 unconfirmed transactions on 5 August 2026, its highest level since February 2025. Daily active addresses reached 712,000, a three-month high, and transfers of more than $1 million came in at 61,800, a five-month high. CoinDesk's daybook and a separate on-chain report published the same morning agreed on the driver: not trading but the Coldcard exploit, with owners of affected hardware wallets moving coins off compromised seeds and onto new ones. That pattern fills blocks without moving price. The day's tape bore that out.

Three metrics, one direction

All three on-chain series moved together. The mempool print of 89,031 was the standout, since it measures demand for block space in real time rather than settled activity. Active addresses at 712,000 and whale transfers at 61,800 are counts of distinct participants and large-value movements respectively; both sat at multi-month highs, not multi-year ones. The session underneath was calm. Bitcoin took $64,000, though the outlets covering it published levels ranging from $64,046 to $64,597 depending on the timestamp, and US spot bitcoin ETFs took $244.42 million, the strongest single day of the week. One market tracker, the only outlet to publish derivatives figures for the session, put total open interest across crypto at $114 billion. Its liquidation count was $204 million over 24 hours, spread across 69,047 traders.

Sweeps off a 2021 seed flaw

The congestion traces to the 2021 firmware flaw in Coldcard hardware wallets, which routed seed generation to software randomness and cut effective key strength from 128 bits to as little as 40. Coinkite, the manufacturer, had told owners to migrate to fresh seeds, and each migration is a transaction, often a consolidating one that spends many inputs at once. Loss estimates were still moving as of 5 August, and the published figures did not agree: Galaxy Research put the total at roughly 2,055 BTC, over $100 million, while CoinDesk's daybook that morning used $120 million. Both are on the record. The figure moved daily through the week.

Smaller than the July address spike

The 712,000 active-address print should not be read as an escalation over the end of July, when the same series ran between 978,000 and 980,000 and set a 20-month high. The August reading is a three-month high on a different measurement window, not a new peak, and the two prints reflect the same underlying event at different stages. What is genuinely new in the 5 August data is the mempool, which had not been at this level in roughly 17 months. Congestion driven by migration also has a natural ceiling: it ends when the coins that can be moved have been moved.

Where the swept coins settle

The open question is what the backlog looks like once the sweeping stops, and no dated figure for that existed on 5 August. No exchange-balance or supply-in-profit series was published with a matching as-of date, so whether the migrated coins went to new self-custody setups, to custodians or to exchanges cannot be answered from the on-chain prints alone. The loss total is the second unresolved number: it moved daily through the week, and nobody publishing on the incident had reconciled Galaxy's estimate with the $120 million figure in circulation that morning. Until someone does, the mempool is the cleanest available proxy for how much of the migration is still ahead.