A panned deal.

Semiconductor company Broadcom Inc. (AVGO) retreated 14% to $209.94 in Thursday trading as questions were raised about the rationale for its $19 billion deal to buy software firm CA Inc. (CA) so soon after making a failed bid for Qualcomm (QCOM) . However, CA shares rose 18% to $44.15 at the end of the day.

Under the terms of a merger agreement announced late Wednesday, CA shareholders will receive $44.50 per share in cash -- a premium of 20% over the stock's trading price Wednesday's close before the firms announced the deal. Both companies' boards have approved the tie-up.

Broadcom CEO Hock Tan said the purchase would give the company a foothold in selling subscriptions to software for corporate IT businesses.

"This transaction represents an important building block as we create one of the world's leading infrastructure technology companies," Tan said. "With its sizeable installed base of customers, CA is uniquely positioned across the growing and fragmented infrastructure software market, and its mainframe and enterprise software franchises will add to our portfolio of mission critical technology businesses."

But Nomura Instinet analyst Romit Shah lowered his Broadcom price target to $225 from $250 after Broadcom announced the move. "To say this came out of the left field would be an understatement," Shah said, noting synergies are "not obvious."

Four months ago, President Donald Trump blocked Broadcom's $117 billion bid for fellow chip giant Qualcomm on grounds that the consolidation would threaten national security, as Broadcomm was headquartered in Singapore at the time. That action was spurred by a request from Qualcomm to the Committee on Foreign Investment in the United States, or "CFIUS." But subsequently, Broadcom relocated its headquarters to California.

Sanford Bernstein & Associates analyst Stacy Rasgon wrote Thursday morning that while software sales weren't a previous part of Broadcom's business, "on a purely financial stand-alone basis, we could argue that CA has the typical characteristics of a franchise as AVGO defines it, with an extremely profitable, sticky mainframe business coexisting with an enterprise segment that appears ripe for rationalization."

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