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.
(Read More: Dimon: I wouldn't have left If I lost leadership vote)
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But soon after the acquisition, the plants became a losing business that relied on "inefficient" and outdated technology.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."
—By Ben Protess and Jessica Silver-Greenberg of The New York Times