The U.S. Department of Justice has initiated a civil antitrust lawsuit challenging the proposed acquisition of Vulcan Materials Company’s ready-mix concrete operations in California by Taiheiyo Cement Corporation and CalPortland Company. The case, filed on May 21, 2026, in the United States District Court for the District of Columbia, alleges that the acquisition would violate Section 7 of the Clayton Act, which prohibits mergers that may substantially lessen competition.

Along with the complaint, the Justice Department submitted a proposed Final Judgment requiring the defendants to divest several key assets related to the ready-mix concrete plants in California. These divestitures include CalPortland’s ready-mix concrete plants in Escondido and Oceanside, as well as a leasehold interest in Vulcan’s Lakeside plant. Additionally, the defendants must relinquish leasehold interests for the parcels of land housing the Oceanside and Lakeside facilities. The proposed remedy also mandates the transfer of fifteen CalPortland ready-mix concrete trucks serving the Escondido and Oceanside plants, along with various licenses, permits, and records tied to the divested operations.

The government’s Competitive Impact Statement, filed June 5, outlines the details of the alleged anti-competitive effects, describes the Final Judgment provisions, and explains the legal remedies available to private parties potentially harmed by the merger. The Justice Department contends that the acquisition would reduce competition in the supply of ready-mix concrete in the California market, potentially leading to higher prices or reduced services for customers.

The complaint and accompanying documents are publicly accessible on the Antitrust Division’s website and available for review at the District Court clerk’s office. The Department of Justice has invited public comments on the proposed settlement, with a 60-day window following the initial publication of the notice for submissions. Comments may be submitted by mail or email and will be posted online, filed with the court, and possibly published in the Federal Register.

Taiheiyo Cement Corporation, CalPortland Company, and Vulcan Materials Company have not publicly commented on the lawsuit. The Department of Justice’s action reflects ongoing scrutiny of consolidation trends in industries critical to infrastructure and construction, aiming to preserve competitive market conditions.