F2Pool.

F2Pool was started in Beijing in May 2013 by Chun Wang and Mao Shixing, who goes by DiscusFish online. It grew out of a private pool begun in 2011, and Mao had already started the first Chinese Bitcoin and Litecoin forums, according to Cobo, a company he later co-founded. F2Pool mined both coins from the start; its first Bitcoin block, 234,649, came on 5 May 2013. For its first few years its blocks were signed 七彩神仙鱼, Chinese for “discus fish”, and they still carry a fish emoji. In 2014, F2Pool says, it overtook GHash.IO, another early pool, to become the largest mining poolMining poolA group of miners who share the work of finding blocks and split the rewards, so each gets paid steadily instead of rarely., with up to 30% of Bitcoin’s hashrateHashrateHow many guesses a second all of Bitcoin's miners make together. More hashrate makes the network harder to attack., the computing power spent on mining. By mempool.space’s count it has found more than 100,000 blocks, about one in ten of all Bitcoin blocks so far.

Some of Bitcoin’s landmark blocks are F2Pool’s. Before the 2020 halving, when the new bitcoin paid for each block fell from 12.5 to 6.25, it found the last block at the old amount, 629,999, and wrote in it “NYTimes 09/Apr/2020 With $2.3T Injection, Fed’s Plan Far Exceeds 2008 Rescue”, echoing the newspaper headline about bank bailouts that Satoshi Nakamoto put in the genesis block. In 2021 it found both the block that locked in the TaprootTaprootA 2021 upgrade that added Schnorr signatures and addresses starting bc1p, making complex payments cheaper and more private. upgrade, 687,284, and the first block under Taproot’s rules, 709,632.

In September 2023 its block 807,057 brought it a fee of 19.82 bitcoin, paid by mistake on a transaction moving 0.074 bitcoin: every fee in a block goes to whoever finds it, with the new bitcoin, in the block’s first transaction. Chun Wang said F2Pool would hold the coins for three days for their owner to claim, then share them among its miners. Five days after the mistake, having checked who sent them, F2Pool refunded the whole fee to the sender, the US company Paxos.

Two months later, in November 2023, the developer 0xB10C, who compares pools’ blocks with the transactions they could have included, reported that four F2Pool blocks had left out transactions from an address on the US Treasury’s sanctions list, “likely filtered”. Chun Wang replied on X: “Why do you feel surprised when I refuse to confirm transactions for those criminals, dictators and terrorists? I have every right not to confirm any transactions from Vladimir Putin and Xi Jinping, don’t I?”

Many Bitcoin users see censorship resistance, the idea that nobody can stop a valid transaction, as a core principle, while many officials worry that blockchains can be used to finance crime and terrorism, CoinDesk noted. Wang argued that such a system “must be designed to resist censorship at the protocol level, rather than relying on each participant to act conscientiously”. Within hours he wrote that F2Pool would “disable the tx filtering patch for now, until the community reaches a more comprehensive consensus on this topic”, then deleted both posts. In January 2025 0xB10C found signs that F2Pool might be filtering such transactions again; every one it left out was confirmed in the following blocks.

F2Pool left its home market in 2021. After China’s government moved against cryptocurrency businesses that September, it told its users in mainland China: “Due to the recent development in local regulation, we will no longer be able to provide you with mining pool services.” It planned to close its service there by the end of the year. In 2024 it merged with stakefish, another company Chun Wang co-founded, and it is now run by Fram Farm Inc., a company registered in the British Virgin Islands. Wang, by then a citizen of Malta, paid for and commanded Fram2, a SpaceX flight that in April 2025 became the first to carry people over Earth’s poles. Mao now runs Cobo, a custody company that holds cryptocurrency for businesses.

Cobo has also held F2Pool’s rewards: in April 2024 mempool.space’s mononaut found that it held the keys to the addresses receiving the block rewards of F2Pool, AntPool and several other pools. But F2Pool still chooses the transactions in its blocks itself, 0xB10C found: the block plans it sends its miners matched no other pool’s. It also sells priority. Its transaction acceleratorTransaction acceleratorA service, usually run by a mining pool, that tries to include a stuck payment in its next block, sometimes for a charge., a service for speeding up a waiting transaction, gives that transaction priority in blocks found by F2Pool and the other pools it works with, so it is confirmed sooner only when one of them finds a block.