Bitcoin’s blockchain experienced a rare two-block reorganization at block height 941,880 on March 23, 2026, involving three of the network’s largest mining pools. The event, in which two previously confirmed blocks were orphaned and replaced, has drawn attention from researchers and traders alike, though it falls squarely within Bitcoin’s designed consensus behavior.
The reorganization unfolded when mining pools AntPool and ViaBTC each mined competing blocks at heights 941,881 and 941,882 on one chain, while Foundry USA simultaneously produced its own versions of those same blocks on a parallel chain. Both chains temporarily coexisted at equal length.
Foundry USA broke the tie by mining block 941,883, then 941,884, and 941,885, extending its chain to seven consecutive blocks from height 941,879 through 941,885. The AntPool and ViaBTC blocks became orphaned “stale” blocks, permanently discarded from the ledger.
What Is a Block Reorg and Why Does This One Stand Out?
A blockchain reorganization occurs when two competing chains of blocks exist at the same time and the network resolves the conflict by adopting the longer (heavier) chain. The shorter chain’s blocks are discarded, and any transactions exclusive to those orphaned blocks return to the mempool for re-confirmation.
Chain Reorganization Depth
2 Blocks
at block height 941,880 — March 23, 2026
Pools involved: Foundry USA • AntPool • ViaBTC — two-block reorgs are significantly rarer than single-block reorgs, which occur roughly once every 47 days.
A “two-block” reorg means two previously confirmed blocks were displaced at once. Single-block reorgs, where one orphaned block is replaced, occur roughly once every 47 days on Bitcoin and are considered routine. Two-block reorgs are far less frequent, making this event notable for network observers.
The distinction matters because the deeper a reorg goes, the more confirmed transactions it can potentially displace. A single-block reorg affects only the most recent unconfirmed layer, while a two-block reorg reaches one layer deeper into what users may have already considered settled.
Why Two-Block Reorgs Are Exceptionally Rare
Bitcoin researcher b10c described the event as “rare-ish,” noting that single-block reorgs happen periodically but multi-block reorganizations are uncommon on a network with Bitcoin’s hashrate and block propagation speeds.
Foundry USA — Winning Chain
7 Blocks
consecutive — heights 941,879 – 941,885
Foundry’s longer proof-of-work chain replaced the AntPool + ViaBTC fork. Orphaned blocks are discarded from Bitcoin’s permanent ledger with no lasting harm to the network.
For a two-block reorg to occur naturally, two mining pools must independently find valid blocks at nearly the same time, not just once but twice in rapid succession. This requires an unusual coincidence of network propagation delays and hashrate variance across geographically distributed mining operations.
The three pools involved, Foundry USA, AntPool, and ViaBTC, collectively control a substantial share of Bitcoin’s total hashrate. When pools of this size find competing blocks simultaneously, the resulting fork can persist longer than typical before one chain pulls ahead.
This is categorically different from a malicious 51% attack. An intentional reorg would require an attacker to sustain majority hashrate while secretly building a longer chain, an operation that would cost billions of dollars on Bitcoin’s current network. In the same way that Tangem recently warned users about fraudulent schemes impersonating trusted brands, the crypto community must distinguish between genuine security threats and normal network behavior. The March 23 event shows the hallmarks of natural variance: competing blocks from independent pools, resolved quickly through normal proof-of-work mechanics.
What the Reorg Means for Users and Network Security
Transactions included in the two orphaned blocks were not permanently lost. When blocks become stale, the transactions they contained return to the mempool and are typically re-confirmed in subsequent blocks within minutes. For most users, the event was invisible.
Whether any transactions were reversed or double-spent as a direct result of this reorg has not been independently confirmed. The event underscores why exchanges and payment processors require multiple confirmations before crediting deposits. Most major exchanges require between three and six confirmations for Bitcoin transactions, a threshold specifically designed to absorb reorgs of this depth.
For context, Bitcoin had rallied to approximately $70,892 at the time of the event, up 4.54% over the prior 24 hours. There was no visible price impact from the reorg itself, and market participants appear to have recognized it as a technical curiosity rather than a security threat.
The standard recommendation of waiting for six confirmations before treating a large Bitcoin transaction as final remains sound. At six blocks deep, the cost of reversing a transaction through an intentional reorg becomes astronomically expensive, well beyond the reach of any known mining entity.
A naturally occurring two-block reorg, while notable enough to draw researcher attention, does not indicate a systemic weakness in Bitcoin’s consensus model. It is, as b10c put it, “rare-ish,” a reminder that proof-of-work consensus is a probabilistic system that resolves conflicts exactly as designed. The broader crypto market continued trading normally, with sentiment remaining firmly in “Greed” territory on the Fear and Greed Index.
Bitcoin’s reorg history is trackable through public block explorers such as Mempool.space, where anyone can verify block heights and mining pool attribution. This transparency is one of the network’s core strengths.
For merchants accepting Bitcoin payments, the practical takeaway is straightforward: confirmation thresholds exist for a reason. A two-block reorg is absorbed entirely by a three-confirmation requirement. The event validates existing best practices rather than demanding new ones.
Disclaimer: This article is for informational purposes only and does not constitute financial or investment advice. Cryptocurrency and digital asset markets carry significant risk. Always do your own research before making decisions.
