Dimon apologized repeatedly for the loss at the annual shareholder meeting in Tampa, Fla., CNN reported.
"This should never have happened. I can't justify it. Unfortunately these mistakes were self inflicted," he said.
The shareholder meeting lasted less than an hour.
Dimon, in a statement before the meeting, said an internal executive investigation will get to the bottom of the debacle, five days after he disclosed the bank's precipitous loss from a complex web of highly speculative trades tied to corporate debt.
"We maintain our fortress balance sheet and capital strength to withstand setbacks like this, and we will learn from our mistakes and remain diligently focused on our clients, who count on us every day," Dimon's statement said.
A law enforcement source told The Washington Post the Justice Department has initiated a criminal investigation into the massive loss. A Justice Department spokesperson Tuesday declined to comment on the report, the newspaper said.
The risky trades cost one of the highest-ranking women on Wall Street her job.
Ina Drew, a 55-year-old banker who headed the JPMorgan unit charged with the losses, is to receive $14.7 million in equity awards on her departure though those gains could be reduced if she is found to have acted improperly, JPMorgan said in a statement announcing her departure Monday.
Drew received $31.5 million in compensation in the past two years, regulatory filings indicate.
The trades also triggered a Securities and Exchange Commission review, officials said.
The bank's stock-market value has tumbled more than $18 billion since the company admitted Thursday to losing the money over a 15-day trading period. JPMorgan stock was headed higher in early afternoon trading Tuesday, up 3.72 percent.
CNN said preliminary results show shareholders approved of the bank's executive pay packages by a nine-to-one margin. It appears only 40 percent approved a measure calling for an independent board chair, a move that wold have stripped Dimon of some of his power.
That bank's board said it firmly opposed the move, proposed by the pension plan of the American Federation of State, County and Municipal Employees months before the trading debacle.
An independent board chair could cause "uncertainty, confusion and inefficiency in board and management function and relations," the board said in a recent proxy statement.
Dimon has been chief executive officer since 2005 and chairman since 2006.
President Barack Obama used the losses Monday to argue for stricter Wall Street regulation.
At a taping of ABC-TV's daytime talk show "The View," he said: "This is one of the best managed banks. You could have a bank that isn't as strong ... and we might have had to step in. That's why Wall Street reform is so important."
Dimon is "one of the smartest bankers we got," Obama said, "and they still lost $2 billion and counting."