JPMorgan Chase & Co. Chief Executive Officer Jamie Dimon called on employees to be vigilant about their language in e-mails and instant messages amid growing regulatory scrutiny of traders’ written communications, said two people with knowledge of his comments.

“Don’t exaggerate, don’t ruminate, don’t bullshit,” Dimon, 57, told employees at a town hall meeting at the bank’s office in London’s Canary Wharf last week, according to an attendee who asked not to be identified because they weren’t authorized to speak publicly. “I’m serious,” said Dimon.

Regulators have swooped on electronic communications among traders in the industry, using them as evidence of wrongdoing in their investigations into the manipulation of benchmark interest rates and the foreign exchange markets. Five firms have been fined a total of $3.7 billion over Libor-manipulation so far.

“We all need to keep a higher standard,” Dimon said at the Oct. 28 meeting.

Firms across the industry and regulators have in recent months been reviewing records of instant messages, e-mails, phone calls and trading data as regulators scrutinize the foreign-exchange market.

Investigators are focusing on an instant-message group dealers set up to share information about their positions and client orders and boast about their trading prowess over a period of at least three years, four people with knowledge of the probe said last month.

Eight Investigations

JPMorgan put its chief currency dealer in London, Richard Usher, on leave last month after his communications with counterparts at other firms were scrutinized by regulators. Usher went on leave by mutual agreement with his employer and hasn’t been accused of any wrongdoing.

Dimon addressed employees as the U.S. Department of Justice conducts at least eight separate investigations into its activities, ranging from its relationship with Ponzi scheme operator Bernard Madoff to last year’s record trading loss attributed to Bruno Iksil, known as the London Whale.

The lender last month posted its first quarterly loss since Dimon took over as CEO following a $7.2 billion charge to cover the cost of rising litigation and regulatory probes.

Rabobank Groep, the co-operative formed in 1898 to lend to Dutch farmers, was last month fined 774 million euros ($1 billion) and Chairman Piet Moerland resigned after traders’ e-mails showed the routine manipulation of benchmark interest rates such as the London interbank offered rate. Internal e-mails cited in the U.S. Justice Department’s case against the bank were laced with jokes and requests to raise or lower rates depending upon the traders’ positions.