Iksil, unlike JPMorgan traders who buy and sell securities on behalf of customers, works in the chief investment office. The unit is affiliated with the bank's treasury, helping to control market risks and investing excess funds, according to the lender's annual report.

"The chief investment office is responsible for managing and hedging the firm's foreign-exchange, interest-rate and other structural risks," Evangelisti said. It's "focused on managing the long-term structural assets and liabilities of the firm and is not focused on short-term profits."

Iksil probably traded under close supervision at JPMorgan, said Paul Miller, an analyst at FBR Capital Markets in Arlington, Virginia.

"The issue is how much capital they're putting at risk," said Miller, a former examiner for the Federal Reserve Bank of Philadelphia.

A U.S. curb on proprietary trading at banks, meant to reduce the odds they'll make risky investments with their own capital, is supposed to take effect in July. Regulators are still determining how the so-called Volcker rule will make exceptions for instances where firms are hedging to curtail risk in their lending and trading businesses.

Wall Street banks including JPMorgan, Goldman Sachs Group Inc. and Morgan Stanley have submitted comment letters and met with regulators to discuss their complaints about the rule.

"Several agencies claiming jurisdiction over the Volcker rule have proposed regulations of mind-numbing complexity," JPMorgan Chief Executive Officer Jamie Dimon said in his annual letter to shareholders released this week. "Even senior regulators now recognize that the current proposed rules are unworkable and will be impossible to implement."

JPMorgan had $4.14 billion of combined revenue last year from the chief investment office, treasury and private-equity investments, according to the annual report. The treasury and chief investment office held a combined $355.6 billion of investment securities as of December 2011, up 14 percent from a year earlier, according to a year-end earnings statement.

Chief Investment Officer Ina Drew, who runs the unit, was among JPMorgan's highest-paid executives in 2011, earning $14 million, a 6.8 percent pay cut from 2010, the bank said in a regulatory filing this week. Drew referred a request for comment to Evangelisti.

Iksil joined JPMorgan in 2005, according to his record with the U.K. Financial Services Authority. He worked at the French investment bank Natixis from 1999 to 2003, according to data compiled by Bloomberg.