Raphael Gray, 18, was arrested on Saturday for Internet fraud after a joint operation between the U.S. Federal Bureau of investigation (FBI) and Welsh police.
The FBI said on Saturday that losses connected to the alleged activities of Gray and another unnamed 18-year-old could exceed $3 million (1.9 million pounds).
But Gray, the self-styled "Saint of E-commerce", said: "I just wanted to prove how insecure these sites are. I have done the honest thing, but I have been ignored."
Gray and his accomplice allegedly e-mailed credit card details, including those of Gates, to NBCi, a subsidiary of the NBC broadcasting group, the Telegraph said.
The 18-year-olds are said to have used the screen name "Curador" -- Welsh for custodian and allegedly hacked into nine e-commerce Web sites around the world, stealing credit card information related to more than 26,000 accounts from web sites in the United States, Canada, Thailand, Japan and Britain
The arrests stemmed from an FBI investigation conducted with the Welsh police, the Royal Canadian Mounted Police and Internet security consultants, the FBI said, adding that the international banking and credit card industry also provided substantial cooperation.
The FBI was still investigating a wave of cyber attacks last month that disrupted some of the Internet's most popular sites.
The FBI's own Web site was attacked on March 14, the same day the agency celebrated the 50th anniversary of its "Ten Most Wanted Fugitives" list, which is publicised on the site, FBI officials said.
Gray and the other man were questioned and have been released on bail.