Hock Tan, CEO of Broadcom
Broadcom shares fell as much as 4 percent Wednesday after Sen. Rand Paul called for a review of the company's proposed merger with CA Technologies.
The stock, which had traded lower all morning, hit a session low of $234.79 in midday trading before paring some losses. Shares were last seen roughly 1.6 percent down.
CA Technologies were down roughly 2 percent at 12:25 p.m. in New York.
Paul called for a review of the proposed $19 billion merger during a Senate hearing on homeland security.
Play Video Broadcom's stock plunges on CA Technologies deal 
It would be the second major challenge to a Broadcom merger this year. President Donald Trump blocked the chipmaker's proposed deal with Qualcomm in March, citing national security concerns within the Committee on Foreign Investment in the United States.
"If [CFIUS] were looking at Broadcom previously, just because Broadcom has changed their domicile to [the U.S.] doesn't mean we shouldn't still look at Broadcom," Paul said, addressing Secretary of Homeland Security Kirstjen Nielsen.
Broadcom announced in July it had agreed to acquire CA Technologies $18.9 billion in cash. CA Technologies, which makes cloud-based and traditional enterprise software, would help diversify Broadcom, should the deal gain antitrust approvals in the U.S., the E.U. and Japan. The boards of both companies had already approved the deal.
"Broadcom and CA Technologies are both American companies, and there is no basis in fact or law for CFIUS review of our pending transaction," Broadcom said in a statement later Wednesday. "We have received HSR clearance and the approval of CA shareholders, and we have a clear path to completing the transaction in the fourth calendar quarter of 2018."
Broadcom's statement also made reference to an allegedly fraudulent memo related to the merger that the company claims has been circulating around Congress. It was not immediately clear how the memo was related to Paul's comments.
—CNBC's Chloe Aiello contributed to this report.
Play Video Huawei unveils two A.I. chips for cloud computing 
