The antitrust complaint, filed May 21 in U.S. District Court for the District of Columbia, names Taiheiyo Cement Corporation, its subsidiary CalPortland Company, and Vulcan Materials Company as defendants. The government argues the merger may substantially lessen competition in San Diego County in violation of Section 7 of the Clayton Act.
CalPortland and Vulcan are two of the largest producers, distributors, and sellers of ready-mix concrete in San Diego County, according to the complaint. The complaint states that competition between the companies has ensured lower prices and better quality and service for customers.
Under the terms of an October 27, 2025 asset purchase agreement, CalPortland proposes to acquire Vulcan’s competing ready-mix concrete assets in California, including in San Diego County, for approximately $712 million.
The government argues the acquisition risks competitive harm by eliminating substantial head-to-head competition and consolidating suppliers in San Diego County. Combined, CalPortland and Vulcan have a share of over 50 percent in the San Diego ready-mix concrete market, the complaint states.
The suit defines the relevant product market as the production, distribution, and sale of ready-mix concrete, noting the material is unique because it is pliable when freshly mixed and strong and permanent when hardened. Customers will not substitute steel, wood, or asphalt for ready-mix concrete in many building applications, the complaint says.
The relevant geographic market is San Diego County. Because ready-mix concrete is highly perishable and begins to set while being driven to the job site, contractors typically limit the time concrete can spend in a truck to 90 minutes or less. This constraint limits the distance concrete can reasonably be transported, often to a metropolitan area or a portion of that area.
In San Diego County, suppliers with the ability to bid on projects are most often those with plants located within 30 minutes, and to a lesser extent 60 minutes, of driving time to the project site.
The government alleges the proposed acquisition would substantially increase the likelihood that CalPortland would unilaterally increase prices or reduce the quality of its products or service. The presence of other ready-mix concrete suppliers would not be sufficient to constrain a unilateral exercise of market power by CalPortland after the acquisition, the complaint states.
The suit also argues the elimination of CalPortland and Vulcan as independent competitors is likely to facilitate anticompetitive coordination among remaining producers in bidding for customers in the relevant geographic market.
Entry into the market is not timely, likely, or sufficient to prevent the loss of competition, the government contends. Opening a ready-mix concrete batch plant is difficult and time-consuming due to the need to acquire land, obtain zoning variances, and secure environmental permits.
The United States brings the action under Section 15 of the Clayton Act to prevent and restrain the defendants from violating Section 7. California brings the action under Section 16 of the Clayton Act as parens patriae on behalf of its general economy and the health and welfare of its residents.
The plaintiffs request that the court adjudge the proposed acquisition unlawful, preliminarily and permanently enjoin the defendants from consummating the deal, and award costs for the action.