Two Bitcoin mining pools mined over 51% of all BTC in the last three years

Bitcoin (BTC) is often praised by its supporters as the most decentralized cryptocurrency, but the truth may be something else. According to Onchain data, there are only two Bitcoin mining pools that have mined more than 51% of BTC in the past three years. There is a reason why it is important and can raise centralized alerts for major blockchain networks.

Finbold has obtained this information mempool.space,Bitcoin data aggregator and block explorer were collected directly from the observer node. Essentially, this data ranks the Bitcoin mining pool for each mined block for the total block mined over a particular period.

Over the past three years starting March 28, 2025, Bitcoin mining blocks have been very dominated by two mining pools.

To be precise, Foundry USA issued 46,076 blocks (28.72%) and Antpool 34,365 blocks (21.42%) out of 160,432. Together, these mining pools have mined 90,441 blocks, or 56.37% of the total over the past three years.

Why is it important that there are only two mining pools above the 51% threshold?

According to a white paper written by Nakamoto At, Bitcoin’s value proposition lies in achieving consensus on the blockchain state in a decentralized way. This is achieved via Bitcoin mining if a special node (miner) uses computational power to break the hash of encryption to discover the block.

Once a block is discovered, the miners earn the right to collect Coinbase, a newly created BTC unit. In addition to Coinbase, miners can also add transactions to blocks to collect their respective fees.

To do this, miners must broadcast discovered blocks in both Coinbase transactions and in all third-party transactions. Other nodes designed by Satoshi follow a long chain. This means adding a chain with more calibration work installed, or more blocks.

There is a theoretical attack called a 51% offensive, and in theory, a bad actor can spend double. Additionally, Bitcoin mining pools may censor transactions as they are intentionally broadcasted if they have sufficient control over mined blocks.

Finbold reported that F2Pool, the third largest Bitcoin mining pool, was arrested and later received a recognized transaction.

In its current state, the Bitcoin network has two Nakamoto coefficients. The Nakamoto coefficient is a metric that measures the decentralization of a blockchain network by determining the minimum number of independent entities (such as miners) required to control or destroy the network.

Bitcoin mining pool, not individual miners or nodes

It appears that each pool is made of a different miner, but it is a pool coordinator, a single entity, which sets up blocks, broadcasts them to the network, collects rewards and distributes them to miners as needed.

Therefore, mining pools are related entities in measuring current blockchain consensus distributed state. It can only be migrated once if it’s too late under a virtual attack, not individual miners or nodes.

We have also seen cases where transaction fees have not been distributed to Antpur miners, but are sent back to the sender, as expected.

Furthermore, Antpur was also the protagonist of another discovery by a well-known pseudonym analyst. B10C. Researchers say the data suggest that the second largest mining pool could have a strong impact on the other five Bitcoin mining pools.

In conclusion, Bitcoin decentralization could be suppressed as an economy of scale dynamics has emerged and has increased the advantage of large miners. The more blocks a mining pool is discovered, the more rewards will be collected from newly issued BTC and transaction fees. This will allow for greater investment in infrastructure, easier access to capital, and further advantages over future block mining.

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