Authorities say Target's payment machines were breached in the past few weeks, and it was bad. Nearly every store in the U.S. and about 40 million credit and debit card accounts may have been affected.

Target corporation said Thursday that the activity happened between Nov. 27 and Dec. 15.

Target says it immediately told authorities and financial institutions after it became aware of the security breach. Now they're working with a third-party forensics firm to investigate the matter.

Target Corp. says if you made purchases at its U.S. stores during the impacted period check your accounts and suspected unauthorized activity should call them at 866-852-8680.