Bitcoin's price has fallen more than 12 percent over the last 24 hours to $5,400, the lowest price for the popular cryptocurrency in more than a year.

Bitcoin's plunge is part of a broader cryptocurrency sell-off. Ethereum has fallen more than 15 percent over the last 24 hours, while Bitcoin Cash is down 18 percent.

Cryptocurrency markets are jittery ahead of a high-stakes "hard fork" of Bitcoin Cash. Rival factions are pushing different, mutually incompatible versions of the spinoff cryptocurrency, and the two versions are scheduled to create separate, competing versions of the blockchain starting on Thursday. The schism could create confusion among users and damage the reputation of the cryptocurrency.

Bitcoin Cash itself was created through another acrimonious hard fork last August. That schism was motivated by a disagreement about the size of blocks in bitcoin's blockchain. Most of bitcoin's developers favored retaining the 1 megabyte block-size limit that was in effect at the time (a hack called segregated witness has increased the effective block size since then). The hard limit contributed to severe congestion on the bitcoin network, pushing transaction fees up to a median of $34 in mid-December. Bitcoin Cash supporters created their own version of bitcoin with a much higher 8 megabyte block size limit (later raised to 32 megabytes)—allowing this rival version of bitcoin to process many more transactions per second with negligible transaction fees.

Now Bitcoin Cash's camp of big-block dissidents is about to divide once again. The schism pits the maintainers of the leading Bitcoin Cash implementation, called Bitcoin ABC, against Craig Wright. Wright is one of the most controversial figures in the bitcoin world. He has claimed to be bitcoin founder Satoshi Nakamoto, but his claim is doubted by a number of bitcoin insiders—Ethereum founder Vitalik Buterin has labeled Wright a "fraud."

The specific technical details of the schism aren't very interesting—Bitcoin ABC wanted to tweak the bitcoin protocol, and Wright's faction favors maintaining something closer to the original design. But the schism has devolved into a power struggle over who will control Bitcoin Cash in the future. Wright's critics worry that having him closely associated with Bitcoin Cash could damage the reputation of Bitcoin Cash.

To be clear, the controversy is internal to Bitcoin Cash, a community that split off from the main bitcoin community more than a year ago. So it's not clear why it should have any negative impact on the value of mainstream bitcoin or other cryptocurrencies. But cryptocurrency trading tends to be highly correlated—when one cryptocurrency starts to fall in value, others often follow.