Bitcoin Cash Split Into Competing ABC and SV Chains

Bitcoin Cash divided into competing Bitcoin ABC and Bitcoin SV branches on November 15, 2018 after miners activated incompatible consensus rules during the network’s scheduled upgrade.

Contemporaneous reporting recorded both branches mining a block at height 556,767: Bitcoin.com produced the Bitcoin ABC block, while Mempool produced the Bitcoin SV block. By The Block’s 3:46 p.m. Eastern update, 14 blocks had been mined under the new rules and the ABC branch led by one block. That was enough to verify an active chain split, but not enough to establish which branch would ultimately retain the Bitcoin Cash name or BCH ticker.

The event mattered beyond a routine software release. Two ledgers descended from the same transaction history, while exchanges, wallets, miners and derivatives providers had to decide which rules and assets they would recognize. Those institutional decisions could determine whether customers received access to both branches and what a BCH-denominated contract represented.

Incompatible rules produced the split

Bitcoin ABC had announced version 0.18.0 on August 20, implementing the November 15 upgrade. Its principal changes were canonical transaction ordering and OP_CHECKDATASIG, an operation designed to validate messages originating outside the blockchain. Bitcoin ABC described both as foundations for future scaling and applications including oracles and cross-chain contracts.

Bitcoin SV rejected that roadmap and proposed different consensus behavior. Crypto Facilities’ pre-fork technical notice summarized the SV rules as re-enabling four older operations—OP_MUL, OP_LSHIFT, OP_RSHIFT and OP_INVERT—raising the permitted operations per script to 500 and increasing the default excessive-block parameter to 128 megabytes.

Both implementations scheduled their new rules around Unix timestamp 1542300000, corresponding to 4:40 p.m. UTC on November 15. Kraken explained that activation depended more precisely on the median time of the preceding 11 blocks reaching that threshold. The branches did not arise merely because developers published rival code; they became separate chains because miners continued producing blocks accepted under incompatible rule sets.

Exchanges became part of the outcome

The split immediately created custody and market-structure questions. Kraken had said it would make its BCH wallets specific to Bitcoin ABC, suspend BCH deposits and withdrawals around activation, and continue BCH trading. It offered no event-day guarantee that customers would receive an alternative-chain asset.

Poloniex took a different approach. Before the fork, it opened trading in provisional BCHABC and BCHSV instruments. Its published policy called for BCH deposits and withdrawals to stop at 14:00 UTC on November 15, the BCH market to freeze at 15:00 UTC, and each remaining BCH balance to be converted into equal quantities of BCHABC and BCHSV. Withdrawals on the resulting chains would remain unavailable until Poloniex considered them stable.

Crypto Facilities faced an additional problem: defining settlement for BCH-dollar futures. Its policy allowed a resulting token to enter settlement calculations only if it satisfied stated listing, trade-count, volume and relative-price thresholds during at least two of the first seven UTC days after the upgrade. That framework showed that a fork created more than an extra token. It changed the underlying reference asset for existing financial contracts.

The result remained unresolved on November 15

Early block counts measured production under each rule set, not economic finality or universal agreement over naming. Hash power could move between networks, exchanges could apply different tickers, and suspended transfers limited price discovery and arbitrage. The absence of chain-wide replay protection also required platforms to manage the risk that a transaction intended for one branch could be reproduced on the other.

No event-day price or return is asserted here. Fragmented venues treated the split differently, and provisional instruments were not interchangeable with fully transferable coins. The defensible November 15 conclusion is narrower: incompatible upgrades produced two functioning Bitcoin Cash branches, while the identity, exchange treatment and relative economic weight of those branches remained unsettled.