Several banks including Barclays, Citigroup and Royal Bank of Scotland have banned the use of most group chat rooms as global probes into alleged benchmark manipulations drive a radical reform of trading floors.
The scandal over manipulation of the Libor interbank lending rateprompted RBS last year to ban unmonitored chat rooms where traders discussed market topics with rivals, two people familiar with those measures said.
"The bank clamped down on this big time. I think we were even going slightly overboard on this," one senior banker said.
Citi two months ago banned chat rooms with multiple banks, restricting instant messages to conversations with traders from one institution at a time. Barclays, which like the other two banks declined to comment, imposed similar bans late last year.
Executives at JPMorgan are also examining whether conversations currently carried out on so-called "multi-dealer" chat rooms should be done bilaterally over the phone, it emerged two weeks ago.
(Read more: Dutch Rabobank fined $1 billion over Libor scandal)
Banks are re-evaluating their messaging systems as they grapple with the fallout from the Libor scandal and a global probe into alleged manipulation of the $5.3 trillion-a-day foreign exchange market, the latest in a series of benchmark-related rate-rigging investigations.
At least eight regulators in the U.K., U.S., Switzerland and Hong Kong are involved in investigations of more than 15 banks. So far at least a dozen traders have been suspended amid suspicions that chat rooms were used to share sensitive client information.