The FBI agent agreed to the exchange, according to the complaint, and Mr. Hicks sent the agent five credit-card numbers three days later.

WSJ: Arrests Made in Massive Online Sting Operation

's X-Charge, a sales agent for his credit-card processor, saying MasterCard had identified "some sort of breach or compromise" within his system.

WSJ: Hackers New Target: Small Firms With Lax Security

Here's why: In the next few months, you may get a letter from your credit card company, insurance agent, or broker that looks like a piece of junk mail.

CNN: How to fight privacy looters