On August 1, a dissident faction of the Bitcoin community created a new payment network called Bitcoin Cash. There are lots of Bitcoin-derived spinoff currencies, of course, but this was unusual because it branched off from the existing Bitcoin blockchain. The result was the cryptocurrency equivalent of a stock split: everyone who owned one bitcoin before the split suddenly owned a "cash" bitcoin after the split.

Today, the value of Bitcoin Cash in circulation is about $20 billion. That makes it the third most valuable currency, after only the original Bitcoin and Ethereum. And this appears to be newly created wealth. The value of vanilla bitcoins didn't fall significantly on the day of the split, and it has since zoomed upwards so that the value of all conventional bitcoins is now around $150 billion.

Source: https://arstechnica.com/tech-policy/2017/11/get-ready-for-a-wave-of-bitcoin-forks/