We've been hearing about Nvidia's attempts to acquire chipset maker ARM since last year, but thanks to some not-so-surprising concerns from the US government, the purchase has yet to be made official. After both companies confirmed in October that the ongoing antitrust probe was far from complete, it seemed like the deal's future was murky at best. Now we know the conclusion of that investigation: an FTC lawsuit meant to put an end to the sale.

The FTC challenged the acquisition in court today, calling the $40 billion deal anti-competitive (via The Wall Street Journal). According to the lawsuit, if Nvidia were allowed to absorb ARM, it would give the company immense control over the technology that its rivals — presumably companies like Qualcomm — need to design chipsets like the recently-unveiled Snapdragon 8 Gen 1. The decision to file the lawsuit was unanimous, with all four members — two Democrats, two Republicans — agreeing the deal was unlawful.

FTC Bureau of Competition Director Holly Vedova issued a statement following the announcement:

“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. Tomorrow’s technologies depend on preserving today’s competitive, cutting-edge chip markets. This proposed deal would distort Arm’s incentives in chip markets and allow the combined firm to unfairly undermine Nvidia’s rivals. The FTC’s lawsuit should send a strong signal that we will act aggressively to protect our critical infrastructure markets from illegal vertical mergers that have far-reaching and damaging effects on future innovations.”

It's the latest in a long line of hurdles Nvidia's acquisition has faced since last year, as the European Commission opened an investigation of its own back in October. For its part, Nvidia has previously stated it wouldn't stop any of its rivals from accessing ARM's designs. However, it seems like major governments around the world are finding it difficult to trust either company at its word. While this turn of events hasn't outright killed the deal just yet, it's yet another bad omen for the future of this acquisition.