AntPool.

AntPool began as the 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. of Bitmain, the Chinese company that makes Antminer mining machines, which Jihan Wu and Micree Zhan founded in 2013. The pool found its first block, 286,681, on 19 February 2014, and has since found more than 111,000, about one in nine of all Bitcoin blocks ever mined and more than any other pool. In 2021 Bitmain spun it off: the legal steps were completed on 1 May, Bitmain said, and with new shareholders AntPool would run its business on its own, outside China. A filing to the US Securities and Exchange Commission in January 2023 gave its holding company’s address as Singapore, and showed that 79.87% of it belonged to a company wholly owned by Zhan, named there as Ketuan Zhan. AntPool’s website lists Bitmain among its “strategic partners”.

Its size gave it a voice in the fight over Bitcoin’s block size, which came to a head in 2017, when AntPool was the largest pool. Wu wanted the limit on how much each block can hold raised. Pools can mark their blocks to show which change they back. On 6 March 2017 AntPool began marking some of its blocks for Bitcoin Unlimited, rival software that would let miners lift the limit, and Wu told Bloomberg: “We will switch our entire pool to Bitcoin Unlimited.”

Roger Ver, Bitcoin Unlimited’s best-known backer, likened the alternative, SegWitSegWitSegregated Witness: a 2017 upgrade that moved signatures into a separate part of each payment, making room for more payments., to a haircut for someone dying of thirst: “Do you drink some water or go to the barber shop? SegWit is like going to the barber shop.” Peter Todd, a Bitcoin Core developer, called Bitcoin Unlimited “irredeemably broken” and warned: “Large miners have every reason to vote the size up to push their competition out of business.” From June, AntPool’s blocks also carried the tag of the New York Agreement, a plan by Bitcoin companies to switch on SegWit and then double the block size. Both tags vanished in November 2017, after the second half of that plan was called off.

Today AntPool finds about one block in five, second only to Foundry USA, and researchers think it builds more blocks than carry its name. Several smaller pools, among them Poolin, BTC.com and Binance Pool, have been found sending their miners the same block templates as AntPool, the draft blocks a pool hands out to be worked on, while putting their own names on the blocks, and their rewards have been moved together with AntPool’s. 0xB10C, a developer who studies mining pools, calls the group “AntPool & friends” and put it at about 40% of Bitcoin’s mining power in 2024. He notes that it isn’t proven one company is behind them all.

Each AntPool block’s first transaction pays the reward, the new bitcoin plus every fee in the block, to AntPool, which pays its Bitcoin miners once a day by FPPS, a set amount for their work, or by PPLNS, a share of what its blocks actually earn. That reward is separate from the transactions the block confirms, but because it includes their fees, a fee paid by mistake goes to the pool. On 23 November 2023 a transaction in AntPool’s block 818,087 paid 83.65 bitcoin in fees to send 55.77.

A week later AntPool said its risk-control system had “temporarily froze the fee when packaging the transaction”, and offered to refund it to whoever could prove control of the sending address by 10 December. Someone claiming to own the wallet had said it was hacked, and mempool.space’s mononaut warned that the refund could go to the thief. Whether anyone claimed it hasn’t been reported.

AntPool also mines more than a dozen other coins; the activity on this page is Bitcoin’s. And it sells a service for speeding up a waiting transaction, which it says it and other pools it works with give priority to.