White House blocks Broadcom's proposed purchase of Qualcomm

Broadcom CEO Hock Tan shakes hands with Trump at the White House. Photo: Martin H. Simon - Pool/Getty Images

The White House tonight blocked Broadcom's proposed $117 billion purchase of Qualcomm, saying preventing the deal was "necessary to protect the national security of the United States."

Why it matters: It is unprecedented for the U.S. government to block a deal like this one. The purchase — which would have been the largest tech deal in history — hadn't even been agreed to yet by the two companies. Blocking it also shows the Trump administration's aggressive stance on perceived threats from foreign investors and the growing technological might of China.