* Irene Tse ran North America side of CIO office
* Latest executive to depart unit after $5.8 bln loss
* Her European counterpart oversaw 'London Whale'
* Tse had job for 21 months
(Adds origin of report, additional quote from memo, stock price)
By David Henry
NEW YORK, Oct 1 (Reuters) - Another top executive at the JPMorgan Chase & Co unit that lost $5.8 billion on derivatives trades this year is leaving the company.
Irene Tse, who headed the North America operations of the Chief Investment Office, told the firm she is resigning to focus on "entrepreneurial ventures," according to a memo on Monday from Chief Operating Officer Matt Zames, a copy of which was obtained by Reuters.
Tse worked opposite Achilles Macris, the head of the European side of the unit who oversaw trading executive Javier Martin-Artajo and trader Bruno Iksil, the man who became known in the credit derivatives market as the "London Whale" for the size of positions he took and that ultimately lost the money.
The loss, initially disclosed in May, exposed major problems with risk controls in the unit and tarnished the reputation of Chief Executive Jamie Dimon, who had complained fiercely about excessive regulation of banks following the financial crisis.
Macris, Martin-Artajo and Iksil were fired by the company in July. At the same time, Ina Drew, the head of the entire CIO, resigned. Their departures came as the company said it had found evidence suggesting that employees had tried to hide the losses.
Tse has been working on JPMorgan's overhaul of the investment office for the past several months, the memo said. The memo said the purpose of that effort is to refocus the unit "to its core mandate of conservative investing as we strengthened our risk management and controls."
The memo called Tse "a great contributor to the group."
JPMorgan shares have recovered from the initial shock of the trading debacle when the stock lost nearly $26 billion in market value in two weeks. The stock rose 1.2 percent to end at $40.97 on Monday. This is 23 cents above the price at the close on May 10, after which the loss was disclosed.
Tse had been hired in January 2011 after working for three years as a portfolio manager at hedge fund operator Duquesne Capital Management. By then the unit had amassed for investment more than $300 billion as deposits piled into the bank during the financial crisis. She was quoted by the company at the time as saying the unit offered "an extraordinary platform for me and the entire CIO group to invest and manage risk."
Before joining Duquesne, Tse was a partner at Goldman Sachs Group Inc where she was co-head of the U.S. interest rates business. She had also been a member of the U.S. Treasury Borrowing Advisory Committee, a panel of financial market experts appointed by the government.
The memo was reported earlier on Monday by Bloomberg News, which cited unnamed sources as saying that Tse plans to start a hedge fund to make investments based on trends in the global economy.
(Reporting by David Henry in New York; Editing by Lisa Von Ahn, Kenneth Barry and Richard Chang)
Keywords: JPMORGANCHASE TSE/