The company is developing a stablecoin -- a type of digital currency pegged to the U.S. dollar -- to minimize volatility, said the people, who asked not to be identified discussing internal plans. Facebook is far from releasing the coin, because it’s still working on the strategy, including a plan for custody assets, or regular currencies that would be held to protect the value of the stablecoin, the people said.

https://www.bloomberg.com/news/articles/2018-12-21/facebook-is-said-to-develop-stablecoin-for-whatsapp-transfers