The loss, which Dimon said stemmed from positions that were "poorly monitored," prompted calls from Congress for tighter bank regulation and triggered criminal investigations by the Department of Justice and the FBI.
The trades in question, made by a CIO group that included Bruno Iksil, nicknamed the London Whale because his positions grew so large, were on so-called tranches of credit-swap indexes, the people said.
Tranches allow investors to wager on varying degrees of risk among a pool of companies. Credit swaps pay the buyer face value if a borrower fails to meet its obligations, less the value of the defaulted debt.
Because JPMorgan had amassed such large positions, even a small change in how the prices were marked may have generated a big difference in the value of the trades, one of the people said.
"It would not be normal to book it at levels that were better than the dealer desk," said Peter Tchir, founder of New York-based hedge fund TF Market Advisers. "That would strike me as a very big issue."
- Bloomberg