Target and Neiman Marcus could be the tip of the iceberg, if a new Reuters report is correct. The organization writes that at least three other US retailers also suffered data breaches "using similar techniques" to the one that penetrated Target last month. Reuters doesn't specify the names of the companies affected, only that they are "well-known US retailers" which do their business in shopping malls, and aren't yet certain whether the people responsible for the Target breach — which exposed up to 70 million names, email address, and phone numbers — perpetrated these cyberattacks as well.

Target's business was notably affected by its breach, with the company announcing that sales might have fallen as much as 2.5 percent compared to the prior year due to the breach, so it's not surprising that other companies might not have come forward to announce that their data had been compromised unless compelled by law. However, Reuters' sources suggest that the other companies experienced smaller breaches than the one at Target, so perhaps the type or amount of data stolen wasn't sufficient to require a major announcement.