08/03/2012 11:32 am ET Updated Aug 03, 2012

London Whale Bruno Iksil Was Urged On By Supervisor Javier Martin-Artajo: Reports

Everyone has a boss, even the London whale.

Sources close to the investigation of JPMorgan Chase's $5.8 billion trading loss say the man made notorious by the episode -- Bruno Iksil, a JPMorgan trader known as the "London whale" for the huge positions he would take -- was urged by his supervisor, Javier Martin-Artajo, to overvalue the trades that ultimately produced the losses, the Wall Street Journal reports.

Martin-Artajo was until recently the credit-trading chief for JPMorgan's Chief Investment Office, the unit where the losses originated. Martin-Artajo and Iksil both left JPMorgan in July, and the company reclaimed about two years' worth of compensation from each man.

Attorneys for both men have denied any wrongdoing by their clients.

The Chief Investment Office reportedly operated under a set of rules and risk controls that were looser than those used elsewhere at the bank. The office reported directly to CEO Jamie Dimon and was supervised less closely than other JPMorgan units, according to the Associated Press.

Dimon, who recently bought 360,000 shares of JPMorgan stock, infamously described the London losses as "a complete tempest in a teapot" in April, although he was reportedly aware at the time that the bank was in a position to lose as much as $1 billion.

Other executives at JPMorgan have been caught up in the scandal. Ina Drew, the bank's former chief investment officer and supervisor of CIO, resigned in May. Drew originally received a pay package worth about $57 million, though JPMorgan later announced it would claw back about two years' worth of Drew's compensation, according to Bloomberg. Last week, JPMorgan announced it would reorganize the entire institution in an apparent effort to create more safeguards against future losses.

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