President Donald Trump blocked Broadcom’s $142bn hostile bid for rival chip company Qualcomm, saying he was acting to protect the national security of the US.

The unprecedented presidential action to prevent a giant merger before it was even agreed threatened to turn the White House into a pivotal player in corporate dealmaking, while thrusting national security considerations to the centre of the wave of consolidation that has transformed the US chip industry over the past two years.

The hostile takeover bid by Singapore-registered Broadcom had already aroused opposition from the Committee on Foreign Investment in the US, an inter-agency group in Washington that vets foreign acquisitions. However, while Cfius warned of possible national security concerns, it had called for a full investigation only a week ago.