Citigroup Teams Up With Rival Banks to Fight Venmo by Reuters @FortuneMagazine September 29, 2016, 9:03 AM EDT E-mail Tweet Facebook Linkedin Share icons Citigroup on Wednesday became the last of the big U.S. banks to agree to allow customers to send instant payments by mobile phone over an industry network that is competing with upstart Venmo. Citigroup c said in a statement that it will begin offering the service early next year over the clearXchange network. ClearXchange has emerged as the industry’s rival to Venmo, a non-bank payment service of PayPal Holdings pypl , which is winning fans among young adults who use it to split apartment rents and dinner tabs. The connection would take place about the same time that the bank consortium operating clearXchange plans to rebrand the network as Zelle. The network was started five years ago as a joint venture of Bank of America, J.P. Morgan Chase jpm , and Wells Fargo wfc . Over time, other banks, including Capital One Financial and U.S. Bancorp, joined the network. Get Data Sheet, Fortune’s technology newsletter. Until now, Citigroup stayed with a service called Popmoney that has connected smaller banks and is operated by Fiserv fisv . In August, Fiserv said it would work to connect Popmoney banks to clearXchange banks. Fiserv acted to make it easier for individuals to send money to one another without regard to where they keep their bank accounts. During the years the banks have taken to create one network, Venmo has blossomed as a kind of social network with a critical mass of millennial generation users.