Japan's SoftBank Group Corp. was forced to abandon its $80 billion deal to sell Arm Ltd to U.S. chipmaker Nvidia Corp. earlier in February, after facing significant pushback from antitrust regulators.

On Sunday, similar regulatory hurdles also forced U.S. arms maker Lockheed Martin Corp. to scrap plans to buy rocket engine maker Aerojet Rocketdyne Holdings Inc. Large mergers the world over are facing antitrust scrutiny like never before, especially in the United States, where the Biden administration has made injecting more competition into several industries one of its top goals. A few other deals have also collapsed recently after facing tough reviews.

Here are some others that are in the crosshairs of antitrust regulators:

Microsoft-Activision Blizzsard $69 billion deal would create the world's third-largest gaming company. Faces tough FTC review.

Rogers Communications $16 billion deal to acquire Shaw Communications is being reviewed by communications regulators in Canada. New management expects deal to close.

CK Hutchison-Cellnex Telecom $11.31 billion deal. UK's competition watchdog has flagged "significant competition concerns" due to the transaction.

Morrisons' $10 billion Rice & Clayton, Dubilier deal. In January, Britain's competition regulator launched a formal investigation into the deal.

MGM-Amazon.com $8.5 billion deal is still under review from EU antitrust regulators and the U.S. FTC.

Sanderson-Farms - Cargill and Continental Grain transaction worth $4.53 billion. Several U.S. senators, , including Chuck Grassley and Elizabeth Warren, have urged a tougher antitrust review of the deal.

Spirit Airlines $2.9 billion to purchase Frontier will create the fifth-largest U.S. airline. Expected to face tough antitrust review.

Simon Schuster-Penguin deal for $2.175 billion. DoJ has sued to block the deal, calling it anticompetitive.