Joe Amon/The Denver Post

JPMorgan Chase, the Wall Street giant whose reputation in Washington has eroded in a matter of months, is now moving to avert a showdown over accusations that it manipulated energy prices.

The nation’s largest bank, which has previously clashed with its regulators, is seeking to settle with the federal agency that oversees the energy markets, according to people briefed on the matter. The regulator, the Federal Energy Regulatory Commission, found that JPMorgan devised “manipulative schemes” that transformed “money-losing power plants into powerful profit centers,” a commission document said.

The potential deal, the people said, is expected to cost the bank about $500 million, a record for the commission, which has adopted a harder line with Wall Street over the last year. For JPMorgan, which reported a record $6.5 billion quarterly profit last week, the fine will hardly dent the bottom line.

The accusations against JPMorgan surfaced this spring in the confidential commission document, reviewed by The New York Times, that outlined a pattern of illegal trading in the California and Michigan electric markets. The document, a warning that investigators would recommend that the agency pursue civil charges, also claimed that a senior JPMorgan executive, Blythe Masters, gave “false and misleading statements” under oath.

It is unclear whether Ms. Masters would be included in the potential settlement, but people close to her said that the regulator was unlikely to file a separate action against her. Initially, investigators planned to recommend that the agency hold Ms. Masters and three of her employees “individually liable,” a move that would have cast a shadow over her long career on Wall Street, where she is known for developing complex financial instruments.

JPMorgan’s Trading Loss

While the bank still disputes the accusations, the recent settlement talks signal a shift in strategy for JPMorgan, which previously declared its intention “to vigorously defend” itself. Other banks, including Barclays, are fighting the commission in similar cases, casting the agency as overly aggressive. A settlement with JPMorgan could undermine Wall Street’s counterattacks and pave the way for more settlements.

With the recent overture, JPMorgan appears to have taken a more conciliatory approach to Washington broadly, as it works to mend relationships with regulatory agencies. Its new tack, advocated by top JPMorgan lawyers, underscores the bank’s realization that it was swiftly losing credibility in Washington.

Within regulatory circles, JPMorgan had become known as something of a bully, a bank quick to strike a combative tone with regulators. In a Congressional report examining a $6 billion trading loss the bank sustained last year, investigators faulted it for briefly withholding documents from regulators. The energy markets regulator also accused the bank of stonewalling investigators.

A settlement with the commission would enable JPMorgan to resolve the embarrassing accusations without fighting a lengthy legal battle. It also would allow the bank to focus on its other legal woes as it remains caught in the cross hairs of at least eight other federal offices. In addition to inquiries stemming from the trading loss, banking regulators are weighing enforcement actions against the bank for the way it collected credit card debt.

Jamie Dimon, JPMorgan’s chief executive who was once known as Washington’s favorite banker, acknowledged in his annual letter to shareholders that “unfortunately, we expect we will have more” enforcement actions in “the coming months.” He apologized for letting “our regulators down” and vowed to “do all the work necessary to complete the needed improvements.”

To reinforce the conciliatory approach, the bank has more readily dispatched executives to Washington. It also committed resources to bolster internal controls, a measure that could appease regulators.

The people briefed on the matter, who spoke on the condition that they not be named, cautioned that JPMorgan and the energy regulator were still negotiating a potential fine. The terms are subject to change. Any action recommended by investigators — settlement or otherwise — requires approval by a majority of the five-member energy commission.

The prospect of a deal with JPMorgan Chase was reported earlier by The Wall Street Journal.

A spokeswoman for the bank declined to comment. The commission also declined to comment.

JPMorgan’s run-in with the energy regulator escalated in March, when investigators sent the document outlining the findings of their inquiry. In response, the bank issued a lengthy response to the accusations in mid-May, the people briefed on the matter said, ultimately spurring settlement talks in recent weeks.

For the energy regulator, a settlement would be the latest in a string of actions against big banks. On Tuesday, the commission ordered Barclays to pay a $470 million penalty for suspected manipulation of energy markets in California and other Western states by some of its traders. The bank is fighting the charges.

Like Barclays, JPMorgan faces accusations stemming from its rights to sell electricity from power plants. The rights come from assets the bank accumulated in the 2008 takeover of Bear Stearns.

But soon after the acquisition, the plants became a losing business that relied on “inefficient” and outdated technology. Under “pressure to generate large profits,” investigators said in the March document, traders in Houston devised a solution. Adopting eight different “schemes” between September 2010 and June 2011, the traders offered the energy at prices “calculated to falsely appear attractive” to state energy authorities. The effort prompted authorities in California and Michigan to pay about $83 million in “excessive” payments to JPMorgan, the investigators said.

In a 2012 filing in federal court, the energy regulator took aim at JPMorgan for attempting to thwart the investigation. The bank, the regulator said, refused to comply with a subpoena seeking e-mails that JPMorgan claimed were confidential because they contained private conversations between the bank and its lawyers.

In the March document, the investigators elaborated on the bank’s pushback. The 70-page document said that the bank “planned and executed a systematic cover-up” of documents that exposed the trading strategy, including profit and loss statements.

The investigators also traced some of the obfuscating to Ms. Masters. After California authorities began to object to the bank’s trading strategy, Ms. Masters “personally participated in JPMorgan’s efforts to block” the state authorities “from understanding the reasons behind JPMorgan’s bidding schemes,” the regulator, known as FERC, said.

The investigators also cited an April 2011 e-mail in which Ms. Masters ordered a “rewrite” of an internal document that questioned whether the bank had skirted the law. The new wording: “JPMorgan does not believe that it violated FERC’s policies.”