UBS has become the latest firm to clamp down on traders' use of electronic chat rooms, imposing a ban on "social chat rooms" and toughening up other rules.

In a memo sent to staff Wednesday, the Swiss bank said all chat facilities must have "an assigned MD level UBS 'owner' who is permanently on the chat, acts as 'moderator' and is responsible for the membership, content and behavior in the room". Internal chats will be allowed only on the firm's own communication tools.