Foundry USA Adds Seven Blocks, Triggers Rare Two-Block Reorg, Reviving Bitcoin Centralization Debate

Foundry USA, Bitcoin's largest mining pool, triggered a rare two-block chain reorganization at height 941,881 by briefly producing seven consecutive blocks on March 23, 2026.

“Bitcoin's mining concentration just showed up in a rare 2-block reorg A 2-block reorg at height 941,881 saw Foundry's chain overwrite blocks from AntPool and ViaBTC, coming days after mining difficulty dropped nearly 8%”

@coindesk

The incident occurred days after Bitcoin's mining difficulty had dropped nearly 8%, creating conditions where mining pools could more easily find blocks simultaneously.

@coindesk

Valid blocks from AntPool and ViaBTC were orphaned from the blockchain as a result of the reorganization.

The network resolved the competing chains as designed by favoring the chain with the most cumulative proof of work.

This demonstrated how shrinking industry margins are concentrating hashrate into fewer, larger mining pools.

The largest pool's ability to produce multiple consecutive blocks increased the odds of creating short-lived competing chains.

Blockchain reorganizations occur when multiple miners find blocks at nearly the same time, creating temporary competing versions of the blockchain.

During this incident, Foundry and AntPool both mined blocks simultaneously, causing a chain split that temporarily divided the network.

CoinDesk

Foundry then produced several consecutive blocks, moving slightly faster than its competitors.

This established Foundry's chain as the version the network would follow.

The blocks mined by AntPool and ViaBTC were effectively erased from the ledger as a result.

These orphaned miners earned nothing for their computational work.

This highlights the competitive nature of Bitcoin's mining where timing and speed determine which blocks ultimately make it into the permanent chain.

The reorganization incident has reignited concerns about mining concentration in the Bitcoin network.

“Table of Contents David Schwartz has reopened a basic question for Bitcoin supporters”

MoneyCheck

Industry's shrinking margins are driving consolidation among mining pools.

While a two-block reorganization does not threaten Bitcoin's overall security, growing concentration increases systemic risks.

Foundry USA's ability to control seven consecutive blocks demonstrates practical implications of this concentration.

Larger pools gain greater influence over which blocks get accepted by the network.

This centralization trend contradicts Bitcoin's original vision of a distributed network.

The trend raises questions about the long-term decentralization of the cryptocurrency system.

Ripple CTO David Schwartz has entered the debate, challenging Bitcoin supporters' core arguments about decentralization.

Schwartz argued that proof of work (PoW) is actually a 'centralizing force' that Bitcoin must constantly resist.

@coindesk

This contradicts the common narrative that PoW inherently promotes decentralization.

'Bitcoin's decentralization doesn't come from its use of PoW,' Schwartz wrote on X.

He suggested that Bitcoin's technological advantages may be overstated.

Its position as the first mover could be more important than its technical design.

Schwartz's comments have drawn significant attention in the crypto market.

They force supporters to reconsider whether Bitcoin's PoW system truly delivers decentralization benefits.

The mining reorganization and subsequent debate have broader implications for Bitcoin's long-term narrative.

“Bitcoin's mining concentration just showed up in a rare 2-block reorg A 2-block reorg at height 941,881 saw Foundry's chain overwrite blocks from AntPool and ViaBTC, coming days after mining difficulty dropped nearly 8%”

CoinDesk

While the two-block reorg was technically minor, it highlighted vulnerabilities in Bitcoin's mining ecosystem.

CoinDesk

These vulnerabilities could become more significant as mining concentration continues.

The timing after the recent mining difficulty adjustment suggests market conditions are exacerbating centralization.

For investors, this raises questions about Bitcoin's decentralized ethos remaining intact.

The network may be gradually becoming more centralized despite its design principles.

The incident serves as a real-world demonstration of theoretical concerns about mining pool dominance.

These concerns relate to Bitcoin's security and sovereignty.