A skilled trader who once said she relished a crisis, Ms. Drew — and the disastrous trade — had become a liability for the firm, whose announcement of the trading loss caused JPMorgan’s shares to plunge 9.3 percent on Friday. It was unclear what type of severance package Ms. Drew will receive.

“It’s not surprising that officials there are taking the fall, but this is one of the fastest movements I have seen,” said Michael Mayo, an analyst with Credit Agricole Securities in New York. “Mr. Dimon gets an A for moving to stem the wrath of regulators, but an F for not finding the problem in the first place.”

With the furor intensifying, former JPMorgan executives said, Ms. Drew was clearly feeling pressure to step down, especially with regulators and members of Congress pointing to the loss as an example of why tighter oversight of the nation’s biggest financial institutions is needed.

“The bank has taken bigger losses in investment banking and elsewhere, but because of the timing, she is being piled upon as this huge failure,” said a former senior executive, who spoke on the condition of anonymity because of the delicate nature of the situation.

Executives said that within the last several months, Ms. Drew told traders at the bank’s chief investment office to execute trades meant to shield the bank from the turmoil in Europe. Ms. Drew thought those bets could protect the bank from losses and even earn a tidy profit, these employees said.

But when market tides abruptly shifted in April and early May, Ms. Drew’s instructions to traders to trim what had become a gigantic bet came too late to avoid racking up losses that could eventually exceed the current $2 billion estimate. Within the bank, there is also ample frustration that instead of reducing the losses, Ms. Drew’s traders may have worsened them.