Ian Descoteaux opened his session at Mining Disrupt Miami 2024 by calling it a very light talk. It was not. The co-founder and chief technology officer of Pow.re, a company he described as mostly self-mining with a hand in the hashrate derivatives market, spent the session setting out why he believed a group of large Bitcoin mining pools were not operating as independent businesses. The session was recorded at the June 24–26, 2024 event. Descoteaux said he has been mining since early 2010 and had heard rumors of pool misbehavior since about 2013, but the rumors came without data. That changed the December before the event, he said, when evidence started to accumulate.
What a proxy pool is
A proxy pool, in his definition, is a mining pool that does not build its own block templates, or that relies on an upstream pool for services such as custody or block generation. On its own, he said, that is not a problem.
It's not a significant issue when it's done transparently.
Ian Descoteaux · 1:55
He pointed to EMCD, whose blocks are marked as built by AntPool, as proxy mining done in the open. AntPool markets a service for building a pool on its infrastructure, BTC.com advertises what it calls cloud pool construction, and ViaBTC runs a white-label pool demo. Those arrangements, he said, are no secret. The trouble starts elsewhere.
It becomes an issue when it's not done transparently.
Ian Descoteaux · 2:27
Evidence one: shared custody
His first and largest piece of evidence was where the money goes. Descoteaux showed pools including AntPool, BTC.com, EMCD and Poolin feeding their account-based payouts into the same small set of addresses, which then pay out to miners. Pow.re confirmed one link itself, he said: when the company bought an S21 from Bitmain, its deposit payment reached one of those addresses within two on-chain hops. Citing Coin Metrics charts, he said AntPool, F2Pool, Binance Pool and several others were all sending payouts to the same addresses, and gave the total for 2024 up to the talk.
Only this year, they receive, only since the beginning of the year, they receive 43,700 BTC.
Ian Descoteaux · 4:56
That represents 36% of all the non-exchange pool payouts.
Ian Descoteaux · 5:03
On-chain analysis, he said, ties those addresses to Cobo, a custody company started by the founders of F2Pool, known as Discus Fish. Cobo runs an off-chain settlement network for exchanges that it calls Loop, and Descoteaux said a number of mining pools appear to use it as well, which would leave Cobo holding most of their payouts. He also showed a chart, posted on X by the researcher mononaut, of pools that should be competitors signing transactions together. Either those pools cooperate to sign, he said, or one custody service holds the private keys for all of them.
Evidence two: identical Merkle branches
The second line of evidence was technical. Every block's transactions are hashed in pairs, over and over, up to a single Merkle root that goes into the block header. A pool hands its miners part of that tree, the branch they combine with the coinbase transaction as they hash. Because a block holds so many transactions, he explained, even a few differences between two pools' blocks should make those branches look completely different.
So the Merkle tree should never look similar.
Ian Descoteaux · 7:46
In his charts, about half the pools did. EMCD, BTC.com, Binance Pool, Poolin and others from the custody slides were working on identical branches. He set aside one pair with a known explanation: ViaBTC and a pool he described as its white label share near-identical trees, which he called normal.
Evidence three: the same cheap transaction
The third line came from transaction accelerators, paid services that push a transaction into a block. The one transaction a pool gives its miners next to the coinbase should be the highest-paying transaction in the block. If it pays a suspiciously low fee, Descoteaux said, it is coming from an acceleration service. He cited a post by the researcher b10c showing AntPool, Binance Pool, BTC.com and others all working on the same accelerated transaction at 9.03 sats per vbyte, which he put at about ten times below the network average at the time. A screenshot he took on a flight to Las Vegas a week before the talk showed the same pools on another transaction at 11 sats per vbyte.
So that means that they are cooperating on their transaction acceleration services.
Ian Descoteaux · 10:47
Two ways to count the hashrate
Descoteaux then put numbers on it. In what he called the best-case scenario, AntPool and the pools around it controlled 37.2% of the network, with Foundry at 29.1% and ViaBTC at 13.9%. His likely scenario grouped every pool he believed was in Cobo's custody.
So, those lists of pools being custodyed by [Cobo] are probably controlling 50.3% of the network.
Ian Descoteaux · 11:36
He called that quite concerning. Both figures were his own estimates from the data he had at the time of the talk.
What miners can do about it
Moving hashrate to another pool, or switching to Stratum V2, does not fix the problem in his view; it only shifts it to other miners.
Well, they're just moving the problem around to me.
Ian Descoteaux · 12:04
His answer was live auditing. Pow.re had been logging everything coming from the mining pools for the previous three months, he said, and was building an auditing and monitoring service for pools.
Well, what we can do is audit the mining pools live and give the data to the miners so that they can make their own decision live on where they are mining.
Ian Descoteaux · 12:17
The plan he described covered work observability metrics for each pool, a warning when a pool starts acting as a proxy, daily verification of pool payouts, and a score and review of every pool, all available by API. He said it would be ready before Q4 2024, and that Pow.re would not charge for it.
Of course, it's going to be given for free to the mining community.
Ian Descoteaux · 12:47
Bitcoin traded at $61,272 on June 24, 2024, the first day of the event. On October 16, 2026, it was at $82,531. The full session, with the charts he walked through, is in the video above.