The SEC found that the Useltons were the driving force behind the spam. Between May 2005 and December 2006, the Useltons obtained cheap stock from at least 13 penny stock companies, then drove up the price of those stocks through manipulative trading, spam e-mails, direct mailers and Internet-based promotions, the SEC said.

The Useltons used networks of compromised computers, called botnets, to send the spam, the SEC alleged.

By matching spam e-mails to the Useltons’ brokerage records and transfer agent records, the SEC determined that each of the market manipulations followed a similar pattern, the SEC said. The two men and the companies they controlled received unrestricted shares from the penny stock companies for little or no money in return for purported financing or promotional activities.