Foundry Wins Bitcoin Mining Race Amid Rare 2-Block Reorg

• Monday saw a rare two-block reorganization on the Bitcoin network at block heights 941881 and 941882.
• Foundry USA Pool emerged as the winner of the mining race, causing blocks produced by AntPool and ViaBTC to become stale.
• The incident was a result of near-simultaneous block discovery and was resolved through Bitcoin's standard proof-of-work consensus rules.

Simultaneous Block Discovery

The Bitcoin network experienced a temporary fork on Monday when competing mining pools produced parallel versions of the blockchain at nearly the same time. The conflict began at block height 941881, which was mined independently by both Foundry USA Pool and AntPool. The divergence continued when ViaBTC extended the AntPool branch by mining block 941882, while Foundry simultaneously worked on its own version of that same block.

Resolution via Proof of Work

Bitcoin resolves these temporary forks using a "heaviest chain" rule, where the branch with the greatest cumulative proof of work is accepted by the network. Foundry USA eventually pulled ahead by mining seven consecutive blocks, making its version of the history the official one. Consequently, the blocks mined by AntPool and ViaBTC were displaced. These are technically known as stale blocks—valid blocks that are not part of the main ledger—and their miners do not receive the associated rewards.

Mining Power and Network Statistics

Data indicates that Foundry USA's significant share of the network hashrate likely played a role in its ability to extend its chain faster than its competitors. According to recent figures:

• Foundry USA Pool controls approximately 32.2% of the total hashrate.
• AntPool accounts for roughly 15.7%.
• ViaBTC holds about 7.2%.

Impact on Transactions

While two-block reorganizations are less common than single-block events, they are a known and expected behavior of the Bitcoin protocol during periods of high competition or network propagation delays. Importantly, no user funds were at risk. Transactions included in the stale blocks were either already present in the winning Foundry chain or were returned to the mempool to be included in future blocks. The event serves as a practical demonstration of the network's built-in mechanism for maintaining a single, decentralized history.