Updated from 2:52 p.m. EDT.
NEW YORK (TheStreet) -- Shares of Yahoo (YHOO) were down on heavy trading volume late Thursday afternoon after the digital information company verified a hack of over 500 million accounts on its site.
More than 23.4 million shares of Yahoo have traded so far on Thursday vs. the 30-day average volume of 10.86 million shares.
The breach, which took place in 2014, is believed to be by a "state-sponsored actor," the Sunnyvale, CA-based company said in a statement.
Information stolen from users included names, email addresses, phone numbers, birth dates, hashed passwords and in some cases, security questions and answers.
Yahoo suspects that no unprotected passwords, payment card data or bank account information was stolen in the breach.
The company said it is working closely with law enforcement, and will notify affected users with instructions on how to secure their accounts.
Earlier today, speculation rose that Yahoo would announce a data hack of over 200 million accounts, Recode reports.
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