The New York office of the FBI has opened an investigation into JPMorgan Chase & Co's $2 billion trading loss, a source familiar with the probe has said today.

Reuters news agency is reporting the source, who requested anonymity because the investigation is ongoing, said the probe was in a "preliminary" stage.

The CEO of JPMorgan Chase won a shareholder endorsement of his pay package today and kept his title of chairman of the board, five days after disclosing a $2 billion trading loss at the bank.

Most ballots were cast before CEO Jamie Dimon revealed the loss.

The vote on Dimon's pay package from last year - $23 million, according to an Associated Press analysis - was non-binding. It passed with 91% of the vote.

A vote to strip Mr Dimon of the chairman's title won only 40%.

Speaking with reporters after the meeting, Dimon said: "The buck always stops with me." Earlier, he told shareholders that the company's mistakes were "self-inflicted."

Mr Dimon was confronted at the meeting by shareholders upset about the trading loss, which has rattled investor confidence in the bank and complicated JPMorgan's efforts to fight tougher regulation of Wall Street.

Investors have pummeled JPMorgan's stock price since the loss was revealed. The stock 12 percent in two trading days and lost almost $20 billion in market value. It recovered slightly today.

There was a heavy police presence at the meeting, in an office park east of downtown Tampa.

Mr Dimon got something of a vote of confidence from President Barack Obama, who appeared on ABC's "The View" for an episode to be aired Tuesday. President Obama used the appearance to press for tighter regulation of Wall Street.

"JPMorgan is one of the best-managed banks there is," the president said. "Jamie Dimon, the head of it, is one of the smartest bankers we got, and they still lost $2 billion and counting."

Mr Obama said the bank was "making bets" in the market for the complex financial instruments known as derivatives. Dimon has said the bank was hedging against financial risk.

A part of the 2010 financial overhaul known as the Volcker rule would restrict banks from some trading for their own profit. Mr Dimon and critics of the financial industry have disagreed over whether the trading in question would violate that rule.

Mr Dimon is likely to repeat his acceptance of responsibility for the bad trade. He said in a TV interview Sunday that he was "dead wrong" when he dismissed concerns about the bank's trading last month.

"We made a terrible, egregious mistake," Mr Dimon told NBC's "Meet the Press."

"There's almost no excuse for it."

On Monday, Ina Drew, the bank's chief investment officer and one of the highest-ranking women on Wall Street, left the bank. Ms Drew oversaw the trading group responsible for the $2 billion loss.