The Diem Association, the consortium Facebook founded in 2019 to build a futuristic payments network, is winding down and selling its technology to a small California bank that serves bitcoin and blockchain companies for about $200m, a person familiar with the matter said.

The bank, Silvergate Capital, had earlier reached a deal with Diem to issue some of the stablecoins — which are backed by hard dollars and designed to be less volatile than bitcoin and other digital currencies — that were at the heart of the effort.