US antitrust officials sued to block chipmaker Nvidia’s proposed $40 billion takeover of Arm, saying the deal would hobble innovation in semiconductors and undermine Nvidia’s rivals.

       The Federal Trade Commission said in a statement that the acquisition would deliver Nvidia vast sway over the market by giving it control over chip designs used by the world’s biggest technology companies, including makers of smartphones, factory equipment and cars.

       “The FTC is suing to block the largest semiconductor chip merger in history to prevent a chip conglomerate from stifling the innovation pipeline for next-generation technologies,” Holly Vedova, director of the commission’s Bureau of Competition, said in the statement.

       Arm, owned by SoftBank Group, is known as the Switzerland of the semiconductor industry. It licenses its technology to hundreds of companies, while competing with none of them. All major chipmakers are Arm customers and many of these companies, including Qualcomm, Intel, and Advanced Micro Devices, sell chips that compete directly with products from Nvidia.