The entire London staff of JPMorgan Chase & Co.'s chief investment office is at risk of dismissal as a $2 billion trading loss prompts the first executive departures as soon as this week, a person familiar with the situation said.

Ina Drew, who oversees the unit, may resign as soon as this week, according to another person, who requested anonymity because the deliberations are private. Joseph Evangelisti, a bank spokesman, said Drew would have no comment. While the firm is examining whether anyone in the unit, which employs a few dozen people in London, sought to hide risks, there isn't yet evidence that's the case, one of the people said.

Chief Executive Jamie Dimon, 56, announced the loss May 10, assailing his firm's handling of trading in synthetic credit securities as “flawed, complex, poorly reviewed, poorly executed and poorly monitored.” Initially, he resisted accepting Drew's resignation, the person said. The incident has given ammunition to proponents of stricter bank regulations.