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.

JPMorgan's whale fail and other big bank disasters:

Loading Slideshow...
  • JPMorgan Chase Loses $2 Billion

    On May 10th, the U.S.'s largest bank JPMorgan Chase announced one of its London trading desks had lost <a href="http://www.huffingtonpost.com/2012/05/10/jpmorgan-chase-london-whale_n_1507662.html?ref=business" target="_hplink">$2 billion on bad bets on credit derivatives</a>.

  • UBS Trader Loses $2 Billion

    Kweku Adoboli, a trader for Swiss bank UBS, lost <a href="http://www.huffingtonpost.com/2011/09/15/ubs-traders_n_963715.html" target="_hplink">$2 billion on unauthorized trades in September 2011</a>.

  • MF Global Collapse

    Brokerage firm <a href="http://www.huffingtonpost.com/2011/10/31/mf-global-to-file-for-bankruptcy_n_1066902.html" target="_hplink">MF Global filed for Chapter 11 bankruptcy</a> in October 2011 after a failed $6 billion bet on European debt.

  • Rogue Societe General Trader Loses $6 Billion

    Hailed as "history's biggest rogue trading scandal" at the time, French trader Jerome Kerviel was convicted in October 2010 of <a href="http://www.huffingtonpost.com/2010/10/05/jerome-kerviel-rogue-fren_n_750464.html" target="_hplink">losing French bank Societe General around $6 billion</a> due to unauthorized trades.

  • Bear Sterns Bought By JPMorgan Chase

    After a run on investment bank Bear Sterns nearly caused its collapse in 2007, JPMorgan bought the firm for $2 a share the following March, <a href="http://www.businessweek.com/bwdaily/dnflash/content/mar2008/db20080316_356646.htm" target="_hplink">Businessweek</a> reports.

  • AIG Largest Single Bailout

    Insurance company AIG became the recipient of the <a href="http://www.huffingtonpost.com/2012/05/08/aig-bailout-realize-15-billion-profit-taxpaers-gao_n_1498645.html" target="_hplink">largest ever government bailout for a single corporation</a> when a $182 billion rescue package saved it from a liquidity crisis following a <a href="http://www.huffingtonpost.com/2012/05/08/aig-bailout-realize-15-billion-profit-taxpaers-gao_n_1498645.html" target="_hplink">downgrade of its credit rating</a> in 2008.

  • Washington Mutual Bankruptcy

    One of the biggest players in retail banking and mortgages during the housing crisis, Washington Mutual filed for Chapter 11 in September 2008, after sustaining losses on billions of dollars worth of mortgage and home loans, <a href="http://www.cnbc.com/id/46793926/WaMu_Emerges_From_Bankruptcy_Protection" target="_hplink">CNBC</a> reports.

  • Citigroup Bailout

    Citigroup came to the brink of collapse after it reported losses around $10 billion in 2007, in part due to failed mortgage investments, <a href="http://money.cnn.com/2008/01/15/news/companies/citigroup_earnings/index.htm" target="_hplink">CNNMoney</a> reported. To keep the bank afloat the government issued <a href="http://www.huffingtonpost.com/2008/11/23/feds-consider-plan-to-res_n_145856.html" target="_hplink">a $20 billion bailout in November of that year</a>.

  • Merill Lynch Shocks Investors With Big Loss

    After projecting a $4.5 billion loss during the third quarter of 2007, Merrill Lynch shocked investors by reporting a $7.9 billion deficit from trading mortgage-backed securities and other structured products, <a href="http://money.cnn.com/magazines/fortune/fortune_archive/2007/11/26/101232838/" target="_hplink">according to CNNMoney</a>.

  • Barings Bank Collapse

    One time star trader Nick Leeson was responsible for sinking British bank Barings after losing $1 billion when an an earthquake struck Kobe, Japan in 1995, causing his investments in the Nikkei to fail as the Japanese stock exchange crashed, <a href="http://www.time.com/time/specials/packages/article/0,28804,1937349_1937350_1937488,00.html" target="_hplink">TIME reported</a>.

Related on HuffPost: