Verizon is unsure whether the Yahoo deal will go through, a top executive said, reported Dow Jones on Thursday.

Marni Walden, executive vice president for Verizon, reportedly "can't say with confidence one way or the other" whether the deal will get done." Verizon is still studying the impact of the second breach, Dow Jones reported.

Earlier Thursday, AOL CEO Tim Armstrong told CNBC he "remains hopeful the deal will close," adding that he will monitor the outcomes of the Yahoo investigation.He would not comment on any potential discounts Verizon — AOL's parent company — may receive.

In December, Yahoo announced that more than a billion user accounts were hacked in 2013. That figure is in addition to the breach of 500 million accounts in 2014.

This story is developing. Please check back for further updates.