Facebook Inc. unveiled plans for a new, global financial system with a broad group of partners from Visa Inc. to Uber Technologies Inc. on board to create a cryptocurrency it expects will one day trade much like the U.S. dollar and inject a new source of revenue.

Called Libra, the new currency will launch as soon as next year and be what’s known as a stablecoin -- a digital currency that’s supported by established government-backed currencies and securities. The goal is to avoid massive fluctuations in value so Libra can be used for everyday transactions across Facebook in a way...