Bitcoin experienced a rare two-block reorganization on Monday, with competing blocks at heights 941881 and 941882 briefly splitting the network before Foundry USA Pool’s branch came out on top.
How the reorg unfolded
The event began when multiple miners found valid blocks at nearly the same time, creating a temporary fork.
Foundry mined its own version of block 941881 while AntPool produced a competing block at the same height.
ViaBTC then extended the AntPool branch with block 941882, while Foundry simultaneously built an alternative version of the same block on its own chain.
Foundry ultimately mined seven consecutive blocks on its branch, making it the heaviest chain by cumulative proof of work.
As a result, the blocks mined by AntPool and ViaBTC became stale — valid blocks that fell outside Bitcoin’s canonical ledger, meaning those miners received no rewards for them.
Pool size and hashrate
Foundry’s dominance in network hashrate likely influenced the outcome.
Foundry USA Pool controls roughly 32.2% of Bitcoin’s hashrate, compared with 15.7% for AntPool and 7.2% for ViaBTC.
Bitcoin developer “b10c” noted that a pool’s chance of finding the next block is proportional to its share of total hashrate, meaning larger pools have a natural statistical edge during short-lived forks.
What happened to the displaced transactions
Transactions included in the stale blocks were not lost.
They either already existed in the winning chain or returned to the mempool for possible inclusion in later blocks.
The episode reflects Bitcoin’s consensus rules operating as designed — nodes reorganized to the heavier chain, restoring a single canonical history.
While single-block reorganizations occur occasionally, a two-block event is less common but still a known outcome of near-simultaneous block discovery and ordinary network propagation.
