[ By Howard Haykin ] Don't look  now, but estimates of JPMorgan Chase's loss from derivatives trading just 'grewsome' - from $2 billion, it may widen to $5 billion, the WSJ reported. CEO Jamie Dimon personally approved the strategy that led to the trades, then reportedly never monitored how they were executed, according to people familiar with the matter that the Journal didn’t identify.  Apparently, Mr. Dimon's failure to closely regulate that activity caused resentment among executives whose departments face tighter oversight. Last Week's Report. It was just last week that JPMorgan announced that it had incurred a $2 billion trading loss on synthetic credit products, or derivatives tied to credit performance.  Mr. Dimon referred to incident involving supposed hedge transactions as "egregious" failures by the bank’s chief investment office. Earlier this week, at the company's annual meeting, Mr. Dimon told shareholders that the company was trying to reposition a portfolio of corporate credit derivatives and used a trading strategy that was "flawed, complex, poorly conceived, poorly vetted and poorly executed." The "Or More" Clause. The bank also noted that the amount, initially estimated at $2bn, could increase by $1 billion or more as it winds down the positions.  A spokesperson for the bank declined to comment on the $5 billion estimate, although it is now widely known that JPMorgan had a serious gap within its management structure at the time the trades were executed - it didn't have a treasurer for those 5 months, the Journal reported in a separate article. All told, JPMorgan’s chief investment office oversees about $360 billion - the difference between deposits and what the bank lends.  Matt Zames, who was appointed to lead the division after the loss was reported, shook up leadership and announced a "renewed focus" on hedging risks.  The loss also has prompted several regulators to initiate investigations, including the Federal Reserve Bank of New York and the SEC.  The Fed is also examining how banks in its district are managing cash after receiving a flood of deposits since the credit crisis.  [Bloomberg, 5/18/12]