Mario Tama / Getty Images JPMorgan Chase chairman and CEO Jamie Dimon.

The FBI has opened a probe of JPMorgan’s $2 billion botched trade, which has wiped out nearly $20 billion in shareholder equity and renewed calls for more aggressive regulation of Wall Street. News of the federal probe, which was first reported by The Wall Street Journal, came as CEO Jamie Dimon faced tough questions Wednesday at the bank’s annual meeting in Tampa, but nevertheless received shareholder support for his $23 million annual pay package. Shareholders also defeated a motion that would have split up the roles of CEO and Chairman. Dimon occupies both positions.

The U.S. government probe is still in its initial stages, and it’s not clear what federal laws JPMorgan may have violated, the paper said, but the bungled trade, which was the result of a huge derivatives bet that spiraled out of control, has also prompted an investigation by the Securities and Exchange Commission. The FBI’s New York field office is leading the inquiry, the paper reported.

Last Thursday, during a hastily-convened conference call, Dimon said the firm’s in-house investment office had lost $2 billion on a portfolio of complex financial derivatives initially designed as a “hedge” to balance out potential losses elsewhere on the bank’s books. Dimon said the bank could face $1 billion in further losses, and added that high-level JPMorgan committees including “audit, legal and risk” are investigating the breakdown.

(More: Will JPMorgan’s $2 Billion Blunder Finally End ‘Too Big to Fail’?)

“This should never have happened,” Dimon told shareholders in Tampa on Tuesday, according to CNNMoney. “I can’t justify it. Unfortunately these mistakes were self inflicted.” Dimon’s pay package received 91% of the votes cast, according to the Associated Press. The motion to split the CEO and chairman failed after only receiving 40% of the votes.

On Monday, JP Morgan replaced the bank’s chief investment officer, Ina Drew, who had been responsible for the division, known as the chief investment office, which made the bad bet. With Dimon’s backing, Drew had in recent years transformed the division from a conservative operation designed to mitigate the firm’s overall risk, into a risk-taking profit center. Other executives from the division are also expected to leave the bank.

Meanwhile, financial reform advocates have seized on the incident as proof that stronger bank regulation is needed. Dimon has been Wall Street’s most vocal opponent of the Volcker Rule, a central part of the Dodd-Frank financial package aimed at preventing banks that can collect government-insured deposits from making risky, so-called “proprietary” bets.

Thanks to vigorous lobbying by JPMorgan and other Wall Street banks, the Volcker Rule includes a loophole that allows the banks to make “hedge” trades, designed to reduce risk. But JPMorgan traders were going much further than hedging, according to Bloomberg, which reported Monday that Dimon himself had pushed to transform the chief investment office into a money-making operation.