Verizon Communications Inc.’s top attorney said it would be reasonable to assume that the hack into Yahoo! Inc.’s e-mail accounts represent a material impact on the phone carrier’s acquisition of the internet company’s online businesses, a person familiar with the matter said.

Verizon hasn’t definitively concluded that there was a material impact and is still waiting for Yahoo to complete its investigation into the situation, said the person, who asked not to be identified discussing private information. Reuters reported earlier Thursday that Verizon General Counsel Craig Silliman saw the reasonable basis for a material impact, which could let the company withdraw completely from the $4.83 billion deal.
Yahoo is confident in its value and continues “to work toward integration with Verizon,” the company said in an e-mailed statement.

Shares of Sunnyvale, California-based Yahoo fell as much as 2.8 percent after the Reuters report. They were down 1.8 percent to $41.62 at 3:43 p.m. in New York, while Verizon’s were little changed at $50.34.

The phone giant agreed in July to acquire the Yahoo core business, beating out AT&T Inc. and Quicken Loans Inc. founder Dan Gilbert in an auction. Verizon has planned to use the transaction to build upon its acquisition last year of AOL Inc., creating a digital advertising business that it hopes could rival Google and Facebook Inc.

Yahoo threw a wrench in that plan last month, notifying Verizon -- and later the general public -- that the personal information of at least 500 million users had been stolen in a 2014 cyberattack. Until now, Verizon hadn’t gone so far as to say the disclosure might alter the terms of the transaction.

Just three days ago, Verizon Chief Executive Officer Lowell McAdam said at a conference in California that the company was “still understanding what was going on and defining whether it was a material impact on the business or not,” according to the Wall Street Journal.

McAdam said the logic behind the merger still made sense and he was impressed with Yahoo’s team, the Journal said.