The moves follow an April article in The Wall Street Journal that detailed Altman’s efforts to have OpenAI back companies he personally invested in. They coincide with a lawsuit brought by Elon Musk in which the billionaire has alleged that Altman and OpenAI manipulated him into giving tens of millions of dollars to found OpenAI as a nonprofit organization, only for them to turn the AI lab into a for-profit venture.

The House of Representatives Oversight Committee on Friday sent a letter to Altman requesting a briefing from a top executive about potential conflicts of interest and documents outlining the company’s governance practices, according to a copy the committee posted to its website Monday.

“The Committee aims to ensure that funds donated for charitable purposes are not diverted for unintended uses, such as artificially increasing the market value of other companies in which an executive or board member may hold an interest,” the House letter from Chairman James Comer (R., Ky.) says. It says the effort is part of an investigation into potential conflicts of interest involving nonprofits.

Comer supported Musk’s work on the Department of Government Efficiency last year, which included targeting nonprofits accused of fraud.

In the Comer letter and the SEC letter, which both cite the Journal’s reporting, the Republicans argue that Altman’s deals with companies he invests in, such as nuclear-fusion firm Helion, could pose conflict-of-interest concerns because OpenAI’s involvement could boost the value of the other companies.

OpenAI board chairman Bret Taylor defended Altman in a court hearing Monday, testifying that Altman had been “forthright” and “proactive and transparent” about his involvements in other companies. Altman recused himself from recent discussions about a deal between OpenAI and Helion as well, The Wall Street Journal reported.

The comments were made during the continuing court case between Altman and Musk. OpenAI has said that Musk not only knew about the for-profit conversion plan but also supported it and asked for unilateral control.

The attorneys general wrote to SEC Chairman Paul Atkins asking him to scrutinize the potential conflicts ahead of the IPO.

The attorneys general from Florida, Montana, Nebraska, Iowa, West Virginia and Louisiana said Altman “has a history of self-dealing and serious conflicts of interest that have created significant risk for the company.” Because Altman has no direct equity in OpenAI, “his personal financial interests have only limited alignment with OpenAI’s financial performance,” the letter says.

OpenAI is expected to quickly become a member of indexes and exchange-traded funds shortly after the IPO because of its gargantuan valuation, recently around $850 billion in the private market. That is set to give many investors exposure to the company.

“Altman’s troubling conduct thus far pales in comparison to the harm that would result if he were permitted to continue this pattern after OpenAI goes public,” reads a copy of the letter viewed by the Journal. The attorneys general ask for close review of documents submitted ahead of the public listing, including the S-1, an initial registration document companies file when they go public detailing their finances and conflicts of interest. “The consequences of any self-dealing by Altman could be borne by our state pensions and individual investors, creating enormous financial risk.”

SpaceX recently acquired Musk’s xAI, a competitor to the maker of ChatGPT. Critics of Musk say he and other OpenAI rivals are trying to turn regulators and the public against the company to keep pace in the AI race.

OpenAI’s IPO is expected to be one of the largest ever. SpaceX and Anthropic, another OpenAI rival, are also expected to pursue IPOs soon.

In addition to asking OpenAI to lead an investment in Helion, Altman last summer asked rocket-maker Stoke Space if it wanted to partner with the company to build data centers in space. Altman is an investor in Stoke Space through his family office, the Journal reported.

Both Musk and Altman are allies of President Trump and have generally supported Republican efforts to adopt industry-friendly AI rules. The SEC under Atkins is bringing fewer enforcement cases targeting Wall Street’s alleged rulebreakers.

Perceived conflicts of interest contributed to the OpenAI board briefly ousting Altman before he was later reinstated. The letter from the attorneys general asks the SEC for more details about his ouster and any governance mechanisms to prevent his potential conflicts of interest from becoming a problem.

Write to Philip Wegmann at philip.wegmann@wsj.com, Amrith Ramkumar at amrith.ramkumar@wsj.com and Berber Jin at berber.jin@wsj.com