Miners who have pointed their hardware at SBI Crypto’s Bitcoin pool have 27 days to find a new home — and where they send their hashrate will do more than solve a personal logistics problem. It will quietly determine whether Bitcoin’s growing concentration in the hands of a few dominant pool operators gets worse, stays the same, or takes a small step back.
SBI Crypto, the mining subsidiary of Japanese financial conglomerate SBI Group, announced Thursday that it will permanently shut down its public Bitcoin mining pool on July 31, 2026. The pool stops accepting mining shares at 07:00 JST on July 31 — 22:00 UTC on July 30 — and any shares submitted after that cutoff will not be counted toward final payouts. CEO Hiroaki Morita signed the customer notice, which urged miners to keep directing their hashrate to the pool right up until the cutoff time to maximize their final payout eligibility. No explanation for the shutdown was offered.
The pool currently accounts for approximately 20.9 exahashes per second (EH/s), or about 2.2% of the Bitcoin network’s total hashrate, according to data from Luxor’s Hashrate Index. That makes it roughly the 11th-largest active mining pool in the world — significant enough that its exit, while not a threat to Bitcoin’s security, meaningfully reshapes the competitive landscape at the top of the mining industry.
SBI Offered No Explanation — but There Is a Paper Trail
SBI Crypto’s shutdown notice said nothing about why the company is leaving the mining pool business. The letter focused entirely on operational logistics: final payout procedures, the share submission cutoff, and a list of three alternative pools the company had previously held “business and technical discussions” with.
But context fills in what the letter omitted. In April 2026, SBI Crypto informed pool customers that it had conducted an internal business review of the mining pool operation and expected to wind the service down by end of July. Before that, in March, the company temporarily suspended its merged mining service for Litecoin and Dogecoin, citing network conditions. It also revised payout schedules and fee structures multiple times over the preceding year.
The background that SBI never addressed publicly is more significant. On September 24, 2025, blockchain investigator ZachXBT — working with security firm Cyvers — identified approximately $21 million in suspicious outflows from wallet addresses linked to SBI Crypto. The stolen assets included Bitcoin, Ethereum, Litecoin, Dogecoin, and Bitcoin Cash. The funds were routed through five instant-exchange platforms and then deposited into Tornado Cash, the cryptocurrency mixing service.
ZachXBT noted that the behavioral patterns in the movement of the stolen funds closely matched techniques documented in previous attacks attributed to North Korea’s Lazarus Group — a state-backed hacking unit that has stolen more than $6 billion in cryptocurrency since 2017. That figure includes the $1.5 billion Bybit theft in February 2025, the largest single cryptocurrency theft in history, which the FBI formally attributed to Lazarus.
SBI Group issued no public statement about the incident and did not respond to press inquiries at the time. The shutdown notice likewise makes no reference to the September 2025 events. The company has never confirmed or denied that a breach occurred. What is documented is the timeline: a major alleged security incident in September 2025, followed by operational restructuring, an internal review in April 2026, and a permanent shutdown announced July 2.
What Pool Closure Actually Means for Network Concentration
The 20.9 EH/s that SBI Crypto’s miners currently contribute to the Bitcoin network will not disappear when the pool closes. Bitcoin’s difficulty adjustment mechanism — which recalibrates automatically every 2,016 blocks, roughly every two weeks — will account for any short-term fluctuation. The miners’ hardware stays on and keeps hashing; only their pool address changes.
That technical nuance is important, but it does not resolve the structural concern. Where those 20.9 EH/s land over the next 27 days will influence how much more concentrated the Bitcoin mining industry becomes — and concentration is already at levels that have drawn consistent warnings from Bitcoin developers and researchers.
As of July 2, 2026, Foundry USA controls approximately 24.3% of Bitcoin’s global hashrate, AntPool accounts for roughly 19.4%, and F2Pool holds around 14%, according to block-production data from mempool.space. SpiderPool and ViaBTC account for another 10% and 8.8% respectively. In total, the five largest pools direct well over three-quarters of all Bitcoin block production. When a mid-tier pool closes, its hashrate flows to the operators that can offer the most competitive fee structures and infrastructure — which, in practice, almost always means the pools already at the top.
The March 2026 chain reorganization illustrated why this matters in concrete terms. On March 23, Foundry USA mined seven consecutive Bitcoin blocks — heights 941,879 through 941,885 — making its chain the heaviest and causing valid blocks from AntPool and ViaBTC to be orphaned. The miners who produced those blocks earned nothing for their work. A two-block chain reorganization of this kind is rare. It is also a direct, on-chain demonstration of what happens when one pool commands enough hashrate to consistently string together consecutive blocks during near-simultaneous mining races.
No attack occurred. The network resolved correctly. But the incident illustrated a core risk that grows as hashrate becomes less distributed: a pool operator running a large enough share of block production gains disproportionate influence over which transactions get included, in what order, and — under the current Stratum V1 protocol — with no accountability to the individual miners whose hardware is doing the actual work.
Block Templates: The Structural Issue Hashrate Concentration Reveals
This is where the architecture of Bitcoin mining matters more than the headline numbers.
Under the current Stratum V1 protocol, which has governed mining communication since 2012, the pool operator constructs the block template. That means a pool operator at Foundry, AntPool, or F2Pool decides which transactions from the global mempool to include in each block their miners produce — and which to leave out. Individual miners receive the template and hash it. They have no say in its contents.
In a world where five pool operators effectively construct the majority of Bitcoin blocks, that is a significant concentration of power — not over the protocol’s consensus rules, but over transaction selection and sequencing. A pool operator under regulatory pressure to exclude specific addresses, for example, could do so without most of their miners knowing. Miners would be unknowing participants in transaction censorship.
Stratum V2, the next-generation mining protocol, was designed specifically to fix this. Its Job Declaration Protocol — the critical sub-protocol in the specification — allows individual miners who run their own Bitcoin full node to construct their own block templates locally, propose them to the pool, and receive authorization to mine against those templates. The pool validates the proof-of-work and handles reward distribution but cannot override the miner’s transaction choices. Block construction authority shifts from a handful of pool operators to thousands of individual miners.
In May 2026, seven of Bitcoin’s largest mining pools — Foundry USA, AntPool, F2Pool, SpiderPool, MARA Pool, Block Inc., and DMND — joined the Stratum V2 Working Group and signaled endorsement of the standard. Together, they represent roughly 75% of global hashrate. This was described at the time as the biggest decentralization shift in Bitcoin mining in years.
But pool endorsement and miner adoption are not the same thing. Under Stratum V2’s Job Declaration Protocol, the decentralization benefit only materializes if individual miners actually run their own Bitcoin node and configure their firmware to use Job Declaration when communicating with their pool. Pools that support Stratum V2 can still operate in “standard channel” mode — where the pool constructs the template just as it does under V1 — if miners do not specifically negotiate for job declaration. As of mid-2026, that miner-side adoption remains limited. The protocol’s authors and community contributors have noted that the gap between pool-level endorsement and actual individual miner deployment of Job Declaration is the specific engineering bottleneck that determines whether Stratum V2’s decentralization promise is realized or merely theoretical.
SBI Crypto’s departure concentrates more hashrate in fewer pools. Whether that matters long-term depends on whether the individual miners — the thousands of operators now being asked to reconfigure their ASICs by July 30 — choose pools that support Stratum V2, and whether they take the additional step of running their own nodes and enabling Job Declaration. Each such choice is a vote on how centralized Bitcoin’s block construction actually becomes.
SBI’s Strategic Pivot: Exchanging Mining for Exchanges
For SBI Group, the pool closure is one side of a larger reallocation of capital and ambition in the digital asset space.
One week before the shutdown announcement, on June 25, SBI Holdings disclosed a ¥46.7 billion ($289 million) agreement to acquire Bitbank, one of Japan’s largest cryptocurrency exchanges and a licensed operator under the country’s Financial Services Agency. The deal — structured through SBI’s investment subsidiary SBICAH — would give SBI full ownership of Bitbank, expected to close around October 2026, pending antitrust clearance from the Japan Fair Trade Commission.
The combined entity would hold SBI VC Trade, SBI’s existing FSA-licensed exchange, alongside Bitbank, creating what would be the largest cryptocurrency exchange operator in Japan by assets under custody — approximately ¥1.1 trillion across 2.9 million customer accounts. Investment bank Architect Partners described the acquisition as SBI “buying regulated scale, not earnings,” positioning the financial group to dominate Japan’s digital-asset market as stricter regulations raise the cost of operating standalone exchanges.
The strategic logic that connects the two announcements is straightforward: Bitcoin mining is capital-intensive, operationally complex, subject to volatile revenue driven by Bitcoin’s price and the network’s difficulty adjustment, and — after the September 2025 security incident — potentially exposed to significant operational risk. Crypto exchange and custody infrastructure, by contrast, generates revenue through fees on trading activity, scales more predictably with regulatory approval, and benefits directly from the consolidation dynamics that Japan’s regulatory environment is driving. SBI Group appears to have made a deliberate judgment about where in the crypto value chain it wants to compete.
What Miners on SBI Crypto Should Do Before July 30
SBI Crypto named three pools in its transition notice: Braiins (the company behind Braiins Pool, formerly Slush Pool — the oldest Bitcoin mining pool, founded in November 2010), Luxor Pool, and NeoPool. All three are established operators with documented track records. SBI stated that it does not endorse any of them and that customers should evaluate each independently; the list was provided because SBI had previously engaged in “business and technical discussions” with all three.
For miners considering where to redirect their hardware, a few distinctions are worth noting:
Braiins Pool natively supports Stratum V2 and offers both FPPS (at 2%) and 0% PPLNS payout models, making it one of the cleaner options for miners who want to take a practical step toward decentralized block construction. Luxor Pool has been expanding its service offerings and has deep data infrastructure through Hashrate Index. NeoPool is a smaller operation.
Miners with larger hardware deployments may also consider splitting hashrate across multiple pools — directing, say, a portion to a larger pool for payout consistency while directing the remainder to a smaller Stratum V2-supporting pool, which both reduces personal payout variance and contributes to distributing Bitcoin’s block construction across a wider set of operators.
The July 30 UTC cutoff — 22:00 UTC on July 30 (18:00 ET) — is firm. Shares submitted after that time will not be counted. SBI Crypto has urged all pool participants to keep directing hashrate to the pool until that final moment, to ensure all eligible work is captured in the payout calculation. Miners who stop early risk leaving earned but unclaimed shares on the table. Final payout schedule details, API access timelines, and web portal access after closure are expected to be communicated by SBI Crypto separately.
Frequently Asked Questions
Does closing SBI Crypto’s pool threaten Bitcoin’s security?
No. The approximately 20.9 EH/s that SBI Crypto’s miners currently contribute will not leave the Bitcoin network — it will be redirected to other pools. Bitcoin’s difficulty adjustment mechanism recalibrates every two weeks, automatically compensating for any temporary hashrate fluctuation. The security concern is structural, not total: it is about which pool operators control block template construction, not about whether enough total hashpower secures the chain.
What is Stratum V2, and why does it matter here?
Stratum V2 is the next-generation Bitcoin mining protocol designed to return block template construction — the process of deciding which transactions go into each block — from pool operators to individual miners. Under the current Stratum V1 standard, the pool operator decides; miners hash blindly against whatever template they receive. Stratum V2’s Job Declaration Protocol allows a miner running its own Bitcoin full node to build its own block template and negotiate it with the pool. Seven major pools endorsed Stratum V2 in May 2026, but the practical decentralization benefit only arrives when individual miners actually configure their hardware to use Job Declaration — and that miner-side adoption remains limited as of mid-2026.
Was SBI Crypto hacked, and does that explain the pool closure?
On September 24, 2025, blockchain investigator ZachXBT identified approximately $21 million in suspicious outflows from wallet addresses linked to SBI Crypto, with behavioral patterns consistent with techniques associated with North Korea’s Lazarus Group. SBI Group never confirmed, denied, or publicly disclosed the incident. The shutdown notice makes no reference to it. The documented sequence — alleged security incident in September 2025, internal operational review in April 2026, shutdown announced July 2, 2026 — does not prove causation, but it is the context in which the unexplained closure took place.
Where should affected miners move their hardware?
SBI Crypto named Braiins Pool, Luxor Pool, and NeoPool as reference options, while explicitly declining to endorse any of them. For miners interested in supporting Bitcoin’s decentralization alongside operational continuity, Braiins Pool’s native Stratum V2 support is a meaningful differentiator. Miners with larger operations might consider splitting hashrate across multiple pools to reduce personal counterparty risk and to avoid contributing further to the concentration of block-production authority at the top of the industry. The migration deadline is July 30 at 22:00 UTC.