JPMorgan Chase & Co. boss James Dimon rode out the financial crisis with one of the most stable management teams in the financial world. That might be about to change.

Two executives on the New York bank's 15-person operating committee, commercial-banking chief Todd Maclin and top international executive Heidi Miller, are expected to step down from those jobs soon, according to people familiar with the matter.

Ms. Miller will likely retire, while Mr. Maclin is expected to take another role within the bank, these people added.

Another ally of Mr. Dimon's, investment-banking chief Jes Staley, has faced questions from subordinates about his strategy and priorities, these people said. Mr. Staley has had the job since late 2009, following the acrimonious ouster of the investment bank's two longtime cochiefs. The unit is the most profitable business at JPMorgan.

The debates within the investment bank and the likely moves among top decision makers at the second-largest U.S. bank add up to a large amount of change at a company known for maintaining unity and continuity near the top. In contrast to Bank of America Corp., Citigroup Inc. and Morgan Stanley, where new chief executives took over during the financial crisis, the 55-year-old Mr. Dimon has been the top executive at JPMorgan since late 2005.

His close-knit inner circle helped the giant bank dodge the huge losses that crippled and even killed some rivals. And the team guided the bank as it gobbled up Bear Stearns Cos. and the failed banking operations of Washington Mutual Inc., emerging from the crisis as one of the strongest banks in America. JPMorgan holds more than 10% of all U.S. insured deposits and has about 243,000 employees.

A JPMorgan spokesman declined to comment on specific executives. "Our team is successful and stable, but there will always be moves among the top ranks of our people," he said. "Change is natural and healthy, and we carefully prepare for it."

Mr. Dimon has indicated to some colleagues that he might remain CEO for five more years. He also recently made it clear, as a result of urging from JPMorgan directors, that the process to pick his successor is under way--and several executives inside JPMorgan are essentially auditioning for the top job.

Mr. Maclin and Ms. Miller weren't considered likely CEO candidates, partly because they are no younger than Mr. Dimon. Mr. Maclin, 55, is expected to step down from his commercial-banking post by year-end, according to people familiar with the situation. He might take a lower-profile job helping oversee JPMorgan's operations in Texas, where he lives.

He also could wind up in a different role that keeps him on the company's operating committee, these people said. Mr. Maclin has worked at JPMorgan or predecessor companies since 1980, and he has been among the most vocal members of the bank's operating committee, disagreeing or protesting on a variety of issues, according to people close to the company. Mr. Maclin's expected successor, Douglas Petno, was moved from a position in JPMorgan's investment bank to its commercial bank, which focuses on medium-size corporate customers.

Ms. Miller is a longtime ally of Mr. Dimon's who now oversees JPMorgan's efforts to expand outside the U.S. People familiar with the matter said she is likely to retire in 2012, and her duties would be absorbed into business units that operate outside the U.S. Ms. Miller is expected to step down "sooner rather than later," one of these people said. For the past two decades, she has worked with Mr. Dimon in a variety of roles. Since last summer, Ms. Miller has been trying to raise JPMorgan's non-U.S. profile by adding offices and bankers.

JPMorgan's next chief executive probably will be chosen from a group of insiders now in their forties, according to people familiar with the situation.

Those executives include Michael Cavanagh, who is in charge of JPMorgan's treasury unit, asset-management chief Mary Erdoes, retail-banking head Charles Scharf and investment-bank executives Matt Zames and Daniel Pinto. Chief Financial Officer Douglas Braunstein also could also emerge as a CEO candidate, one of these people said. Mr. Staley is considered a long shot by some bankers at JPMorgan because he is just a year younger than Mr. Dimon.

The last big upheaval in JPMorgan's top ranks came in September 2009. Mr. Dimon's surprise ouster of longtime investment-bank co-chiefs Steve Black and Bill Winters rocked the unit. The two executives were replaced by Mr. Staley, who previously ran JPMorgan's asset-management division.

Mr. Staley spent a lot of his first year as investment-banking chief outside the U.S., including overseeing an expansion in Asia. But two of his lieutenants soon suggested he spend more time in New York with their trading operations, people familiar with the situation said.

Carlos Hernandez, the head of the investment bank's equities business, told Mr. Staley at a dinner last September that Mr. Staley should move his office from JPMorgan's headquarters to the investment bank's separate building nearby.

At a February meeting where executives discussed an outside study commissioned by Mr. Staley about the investment bank's future, Mr. Zames urged the operating committee to focus first on more immediate issues such as the impact of regulatory reform, according to people familiar with the meeting. Other executives in the room made the same point, these people added.

One person familiar with the meeting said it became "heated." Other people said the discussion wasn't unusual compared with previous meetings by the same group.

A JPMorgan spokesman said Messrs. Staley and Zames disagreed only on "the amount of time the investment-bank operating committee was focusing on its current set of businesses, financial performance and the implications around financial reform." They eventually agreed "the team should focus on specifics around the current business" as well as "invest for growth," the spokesman added.

In March, Mr. Zames, co-head of JPMorgan's fixed-income operation, told his boss that he needed to focus more on the fixed-income business. Mr. Staley agreed, said people familiar with the exchange.

Mr. Staley now has an office next-door to Mr. Zames but intends to move back to JPMorgan's headquarters this fall.

Mr. Dimon said that Mr. Staley and "his team are doing an outstanding job....As individuals and a team, they are working as well, if not better, together than any other investment-banking group I've ever been involved with."

In this year's first quarter, the investment bank had earnings of $2.37 billion, or 43% of JPMorgan's overall net income of $5.56 billion.