Why Two Miners Can ‘Win’ at As soon as
Bitcoin mining is a race with no referee watching the end line in actual time. A brand new block has to bodily propagate (i.e. hop from node to node) throughout a world community earlier than each participant agrees on what the present tip of the chain is. That journey takes seconds, generally longer on a congested connection.
If a second miner finds a legitimate block of their very own earlier than the primary block has completed spreading to them, they construct on the model they final noticed (often the earlier block) and broadcast their very own competing block. For a short window, two equally legitimate blocks exist on the similar top, every with its personal set of confirmed transactions and its personal suggestion for what occurs subsequent.
Neither block is “improper” as each fulfill each rule of the protocol; the one factor separating them is timing and which nodes occurred to listen to about which one first. Roughly half the community finally ends up mining on high of 1 candidate, the remaining on the opposite, and Bitcoin briefly has two trustworthy, simultaneous variations of itself.
How the Tie Truly Will get Damaged
Bitcoin doesn’t resolve this by vote, authority, or whoever technically discovered their block first. It resolves it the identical approach it resolves every thing, i.e. whichever chain accumulates extra proof-of-work turns into the one each node switches to, and the opposite facet’s block or blocks get discarded.
Discarded doesn’t imply destroyed historical past was rewritten, however it implies that that block, known as “orphaned” or “stale,” stops being a part of the chain everybody acknowledges, and any transactions inside it that weren’t additionally confirmed on the successful facet merely drop again into the mempool to be picked up once more in a future block.
More often than not, this resolves after only one additional block, and no person outdoors mining-infrastructure circles notices. A real two-block-deep race (the place the tie in some way survives a whole extra spherical with out one facet pulling forward) is uncommon sufficient to make headlines when it occurs, exactly as a result of it requires the coin-flip odds to land the identical approach twice in a row.
The March 2026 Case: When the Coin Flip Repeated
That’s precisely what occurred on March 24, 2026. After Antpool and Foundry USA every produced their very own model of block 941,881 twelve seconds aside, ViaBTC prolonged AntPool’s model with block 941,882 whereas Foundry, working off its personal tip, prolonged its model too. For one block, the community was genuinely cut up down the center between two legitimate chains. Then Foundry pulled forward, mining blocks 941,883 by means of 941,886 in succession (six consecutive blocks on its department) till its chain was, within the phrases of 1 Bitcoin developer monitoring the occasion, “the heaviest by a large margin.”
Each node reorganized to Foundry’s model, and the blocks AntPool and ViaBTC had mined have been orphaned; their miners misplaced the block reward and charges for that work, although the transactions themselves rejoined the mempool and have been confirmed once more shortly after.
Bitcoin analyst b10c, who first flagged the occasion publicly, known as it “a rare-ish two block fork/reorg between Foundry and AntPool+ViaBTC.” Uncommon is correct, however the occasion additionally drew consideration to a much less snug pattern, i.e. Foundry stringing collectively six blocks in a row is simpler for a pool that already instructions a big share of community hashrate, and protection of the occasion famous that shrinking margins have been pushing smaller miners out and concentrating hashpower into fewer, bigger swimming pools.
A extra concentrated community doesn’t make a single-block race extra widespread, however it does make a well-resourced pool’s odds of successful any given race (and stringing collectively the follow-up blocks that finish one) measurably higher than a small miner’s.
The On a regular basis Model Is Boring, and That’s the Level
Two-block reorgs are the exception; the underlying race situation behind them is just not. Pulling actual block timestamps instantly from mempool.area for the three days earlier than the reorg (heights 941,452 to 941,887), 40 of 435 consecutive-block intervals (about 9.2%) landed inside 60 seconds of one another, together with one pair simply 5 seconds aside. Each a kind of shut calls is a second the place a real race situation, nonetheless transient, existed on the community.
Nearly all of them resolve inside that very same single block, silently, as a result of the following miner to discover a block overwhelmingly simply builds on whichever tip reached them first, and the percentages of two ties in a row are lengthy. Compact block relay and devoted low-latency relay networks like FIBRE, which most giant swimming pools now use, have made the propagation delays that trigger races shorter than they have been in Bitcoin’s earlier years (which is strictly why a race that survives two full blocks, like AntPool and Foundry’s did, is uncommon sufficient to be newsworthy fairly than routine).
