Jonns confirmed his departure but declined to comment on his future plans. TP ICAP, the world's largest interdealer broker, didn't respond to a request for comment.

Two bank interest rate derivatives trading heads said that Jonns was one of the best known and biggest liquidity brokers in the market. He also intermediated short-term rate transactions, said a person familiar with his work. All three people spoke on condition of anonymity.

His departure comes as banks are seeking to reduce trading costs and move to more electronic methods, and away from traditional trading that has been made over the phone or via messages.

Interest rate derivatives is one of the world's largest markets, with $167 trillion in outstanding dollar-based contracts as of year-end, according to data by the Bank for International Settlements.

(Reporting By Karen Brettell; Editing by Alden Bentley and Jonathan Oatis)