The agency’s expected lawsuit against the deal for a health technology company would be the latest move by the Biden administration to quash corporate consolidation.WASHINGTON — The Justice Department plans on Thursday to sue to block a $13 billion acquisition of a health technology company by a subsidiary of UnitedHealth Group, said two people familiar with the matter said, in the latest move by the Biden administration to clamp down on corporate consolidation.The agency plans to argue that a deal by UnitedHealth to buy the health tech firm Change Healthcare would give UnitedHealth sensitive data that it could wield against its competitors in the insurance business, said the two people, who were not authorized to publicly discuss the matter. The suit is expected to be filed in the U.S. District Court for the District of Columbia.A spokeswoman for the Justice Department declined to comment. The companies did not immediately respond to requests for comment.The deal would be the latest transaction to run into opposition from the Biden administration, which has made countering corporate consolidation a central part of its economic agenda. President Biden signed an executive order last year to spur competition in different industries. He also appointed Lina Khan, a prominent critic of the tech giants, to lead the Federal Trade Commission, and Jonathan Kanter, a lawyer who has represented large companies, as chief of antitrust efforts at the Justice Department.Since then, the F.T.C. has blocked Lockheed Martin from buying a maker of missile propulsion systems and the chip giant Nvidia from purchasing the design firm Arm. Even before Mr. Kanter was confirmed, the Justice Department sued to block the merger of two major insurance brokers; the purchase of Simon & Schuster by the publisher Penguin Random House; and a deal that would have married some of JetBlue’s operations with American Airlines’s.The planned lawsuit on Thursday is set to challenge a deal made by Optum, a subsidiary of UnitedHealth that said last year it would buy Change Healthcare, which offers technology services to insurers. UnitedHealth is one of the largest health corporations in the country, with $287.6 billion in revenue in 2021. In addition to its health care information technology business, its Optum unit owns physician practices, a large chain of surgery centers and one of the nation’s largest pharmacy benefit managers.At the center of the D.O.J.’s planned lawsuit is the data that Change Healthcare gathers when it helps process insurance claims. The Justice Department plans to argue that the deal would enable UnitedHealth to see the rules that its competitors use to process claims and undercut them. UnitedHealth could also crunch data about patients at other insurers to gain a competitive advantage, the lawsuit is expected to say, according to the two people familiar with the matter.The lawsuit is also expected to say that UnitedHealth could withhold Change Healthcare’s products — which are used by other insurers — from its rivals or save some of its new innovations for itself, the people said. The Justice Department plans to add that the deal would give UnitedHealth a monopoly over a type of service that is used to screen insurance claims for errors and speed up processing, the two people said.The companies have said that the acquisition will improve efficiency in the industry. They also explored selling the part of Change Healthcare that the Justice Department said would give UnitedHealth a new monopoly.Lawmakers and regulators have increasingly worried that big businesses could use troves of data to hurt their rivals. A congressional committee has investigated whether Amazon uses data from outside merchants who use its platform to develop competing products, for example. Critics of Facebook have also argued that the company having years of user data makes it difficult for an upstart service to challenge its dominance.Since Mr. Kanter joined the antitrust division at the Justice Department, critics have said that he should not oversee cases against companies whose rivals he represented while in private practice. According to a financial disclosure form he filed last year, he once represented Cigna, a major insurer that competes with UnitedHealth, and the remote health care company Teladoc.Mr. Kanter has not participated in the lawsuit against UnitedHealth, one of the people with knowledge of the Justice Department’s case said.Reed Abelson