Those who have worked with Macris, one of several bankers involved in a public storm over last week's disclosure by JPMorgan of a $2 billion plus trading loss, describe him as very smart, someone who liked to think differently about things and not afraid to air his views.
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The 50-year-old, who previously held a proprietary trading role at Dresdner Kleinwort and also spent time at Cardinal Asset Management, joined the U.S. investment bank in London in 2006.
One former employee said bosses in JPMorgan's Chief Investment Office, including Macris and New-York based Chief Investment Officer Ina Drew - who stepped down on Monday - were ambitious and allowed their charges to trade freely in all products except commodities.
In addition to Drew, Macris and another employee involved in the loss-making trades, Javier Martin-Artajo, are expected to be asked to leave the firm, sources close to the matter said on Sunday.
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Neither of the men were immediately available for comment.
"He was a larger than life character, but he wasn't viewed as a reckless guy," said a former colleague who worked with Macris at Bankers Trust in the 1990s.
"He had strong opinions and he expressed them," he said, and this sometimes rubbed people up the wrong way.
One former colleague said he was "sparky", while another described him as "something of a firebrand to say the least", telling of one occasion when, during an argument on the phone, Macris was seen to emerge from his office shadow-boxing.
He then returned to his office and resumed the call.
While no shrinking violet in his working life, the banker, who has both Greek and U.S. citizenship according to online records, leads a more subdued life outside the office.
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Neighbours at his central London flat in a 19th century mansion block, whose residents include a high court judge, company directors and fellow bankers, said they didn't see much of him.
One, pausing on the marble steps of the grandiose building overlooking Westminster Cathedral, said: "I know who Achilles is but I don't know him well. People here keep to themselves."
Other neighbours said he travelled a lot, while a member of staff at the block, who described Macris as "really nice and polite", said the banker and his family were not there often.
One former colleague said Macris had a broad range of interests and could hold a conversation on any topic.
"He just knows everything about everything," he said.
That intellect, and his innovative way of thinking, was part of what made him good at his job, former colleagues said.
"By definition the sort of people who are going to be in that role have to be very smart, questioning people who are looking to do different things," said one, wondering how much Macris could be blamed for the losses.
"If you manage one of the biggest risk positions in the world at different banks over 10 to 15 years, what is the probability that during periods of extreme volatility you are never going to have a black mark against you?"
Copyright @ Thomson Reuters 2012