The network, called Markit Collaboration Services, will be launched on Monday and allows members to chat with one another regardless of the proprietary messaging technology that each firm uses.

This open platform contrasts with Bloomberg LP's messaging system, which is a closed network only for users of Bloomberg terminals.

Bloomberg messaging is the most popular form of chat on Wall Street, and often cited as one of the reasons banks are willing to pay around $20,000 a year for a subscription to a Bloomberg terminal.

Markit and Thomson Reuters said they hoped their open messaging network will attract banks that want to chat with their clients or other financial institutions but cannot currently do so because they are on different messaging systems.

The other banks that have joined the new network are Deutsche Bank, Bank of America Merrill Lynch, Barclays, Citigroup, Credit Suisse and Morgan Stanley, according to a statement from Markit.

The banks collectively employ more than 1 million people worldwide, though it was not immediately clear how many individuals will use the new Markit service.

David Craig, president of Thomson Reuters' Financial & Risk division, said one of the challenges facing banks is that their messaging systems do not always talk to one another. "That creates costs and complexity," he said.

Markit and Thomson Reuters said the messages on the new network are encrypted, and the system does not store them.

Representatives from Bank of America, Deutsche Bank, Goldman Sachs and Morgan Stanley were not immediately available to comment on the new messaging system. Representatives from Barclays, Citi, Credit Suisse and JPMorgan also declined to comment.

(Reporting by Jennifer Saba; Editing by Tiffany Wu and Tim Dobbyn)

By Jennifer Saba