NEW YORK (TheStreet) --Shares of Yahoo! (YHOO) closed higher during trading on Thursday, despite the Santa Clara, CA-based online information company verifying a hack, in which 500 million users' email accounts were compromised.

Recode executive editor Kara Swisher, who first reported the breach, joined Thursday afternoon's "Closing Bell" on CNBC to discuss the hack and the potential impact it will have on Verizon's (VZ) acquisition of Yahoo!.

"Obviously companies get hacked all the time. The question is, the extent of this one is rather massive and from reports that I will be putting up, the company's top executives have been working on this for a long time. They delayed telling people," Swisher explained.

Yahoo! confirmed that the data breach took place in 2014, which begs the question why Yahoo! didn't reset passwords sooner?

"It creates uncertainty around the company, and there's already so much uncertainty around everything else," Swisher said.

Moreover, she noted that former Yahoo! chief information security officer, now chief security officer at Facebook (FB), Alex Stamos was with Yahoo! when the hack took place and advocated for a more aggressive stance. "That obviously never happened," Swisher said.

Regarding the hack's impact on the Verizon deal, Swisher noted that the level of uncertainty surrounding the breach was disconcerting to the telecommunications company.

"I think they are certainly surprised. A lot of sources at Verizon when I called them didn't know about this, and of course, the statement is pretty clear, we just found out two days ago. That's a pretty strong statement of the fact they were not informed adequately about this. I don't know if it will impact it or not, but there are certainly some irritated people at Verizon," Swisher explained.

Separately, TheStreet Ratings objectively rated this stock according to its "risk-adjusted" total return prospect over a 12-month investment horizon. Not based on the news in any given day, the rating may differ from Jim Cramer's view or that of this articles's author.

TheStreet Ratings rated this stock as a "hold" with a ratings score of C.

The company's strengths can be seen in multiple areas, such as its solid stock price performance, revenue growth and largely solid financial position with reasonable debt levels by most measures. However, as a counter to these strengths, we also find weaknesses including deteriorating net income, disappointing return on equity and feeble growth in the company's earnings per share.

You can view the full analysis from the report here: YHOO

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