Information from at least 45.7 million credit and debit cards was stolen by hackers who accessed TJX’s customer information in a security breach that the discount retailer disclosed more than two months ago.

TJX Cos., the owner of about 2,500 stores, said in a regulatory filing late Wednesday that about three-quarters of those cards had either expired at the time of the theft, or data from their magnetic strips had been masked — stored as asterisks rather than numbers.