>> now to what the feds are telling us is the largest data breachen our nation's history. the private information of millions of americans has been stolen from places where they have swiped, debit and credit card . it happened when big name stores were hit by hackers. prosecutors say it went on for years without any one noticing. our report from our senior investigative correspondent lisa myers .  >> reporter: the hackers allegedly penetrated the computer systems of some of the largest companies in the world, jcpenney, 7 eleven , nasdaq, jet blue , heartland and stole a staggering $160 million credit and debit card numbers. the numbers were seld to criminals and used as debit or credit cards and to withdraw from atms costing victims at least $300 million. federal prosecutors called it the largest hacking fraud case in history.  >> this type of crime is really the cutting edge of financial fraud. those who have the expertise and the inclination to break into our computer networks threaten our economic well-being, privacy and ultimately national security .  >> reporter: prosecutors described it as a sophisticated seven-year scheme by experienced hackers. four russians and one ukrainian were charged.  >> once they got in the networks, they would often brag to each other, that when they were in, they "owned" the networks.  >> reporter: the stolen data stored in computer servers in the u.s. and around the world and then sold. $10 for an american credit card number . $15 for canadian. $50 for a european. so far the government says the hundred of millions of dollars in losses have been borne by the companies. officials also say there are unknown costs to individuals whose identities were stolen or who may not have noticed unauthorized withdrawals or credit card charges.  >> the most important thing a consumer can do is to check online cash withdrawals and credit card statements on a regular basis.  >> reporter: prosecutors warn this kind of fraud ultimately costs us all. by increasing the cost of doing business . lisa myers , nbc news, washington.
Video on msnbc.com: In New Jersey, prosecutors brought the largest hacking and data breach case prosecuted so far involving a sophisticated scheme to steal credit and debit card numbers used at 17 big companies. NBC’s Lisa Myers reports.