George Matos Rocha, 51, faced charges that he set off bombs in Lowe's stores in Salisbury and Asheboro, carried a pipe bomb in Randolph County, attempted to extort $250,000 from Lowe's Companies and used the U.S. mail to issue a threat.
Rocha entered the plea during a brief appearance before U.S. District Court Judge James Beatty and answered questions from the judge but made no statement.
Rocha was arrested last month after federal agents traced Internet dealings with a Latvian bank account, which received $250,000 from Lowe's, to his home telephone.
Investigators said Rocha slipped up when he accessed an e-mail account he had created with a fictitious name with his home computer instead of using public computers at libraries, his normal practice.
Federal agents arrested Rocha on Nov. 12 and charged him with bombing Lowe's stores in Asheboro and Salisbury and planting a third bomb at a Concord store. Five people were hurt, one of them seriously.
The FBI's Computer Crime Unit in Charlotte, one of only eight in the country, followed a trail of e-mail messages that led to the Baltic country of Latvia, where a bank account was opened and received the $250,000 Lowe's paid to stop the bombings.
Chris Swecker, FBI special agent in charge for North Carolina, said an FBI agent stationed in the nearby country of Estonia was in contact with the Paritate Bank in Riga, Latvia, "minutes after the money transfer."
The agent determined that the signature on the account was listed as Bruce J. Phillips, a name the FBI soon found to be fictitious.