The fallout continues in the wake of the massive data breach at Target in which hackers stole 40 million debit and credit card accounts from stores nationwide between November 27 and December 15.

USA Today reports that so far three class-action lawsuits have been filed in the wake of the incident, seeking more than $5 million in damages. Two of the cases were filed in California and one in Oregon.

The same USA Today article reports that the Attorney General in at least four states – Connecticut, Massachusetts, New York and South Dakota – have asked Target for information about the breach, in what is regarded as the first step to a possible multi-state investigation into the breach.

Meanwhile, the Krebs on Security blog which broke the story of the Target breach last Wednesday December 18, reports that card accounts stolen in the breach are flooding the underground markets. Check out the latest reports here and here.

For anyone who shopped at Target during the breach period, the New York Times has a helpful Q&A on what you should do.

While latest studies indicate U.S. companies continue to improve their preparation for and response to a data breach, the security breach at Target highlights the vulnerability of major companies to this threat.

Both the organizational cost of a data breach and the cost per lost or stolen record declined last year, according to the 2013 Cost of a Data Breach study by the Ponemon Institute and Symantec.

The organizational cost of a breach declined from $5.5 million to $5.4 million and the cost per record from $194 to $188.

The Ponemon report also noted that while the cost of a data breach can vary widely because of the types of threats and data protection laws, the financial consequences are serious worldwide.

Check out I.I.I. facts and statistics on identity theft and cyber security.