The U.S. Securities and Exchange Commission suspended trading in the securities of 35 companies that have been the subject of recent and repeated spam e-mail campaigns.

The trading suspensions — the most ever aimed at spammed companies — were ordered because of questions regarding the adequacy and accuracy of information about the companies, the SEC explained. The securities of each of the 35 companies have been quoted on the Pink Sheets quotations service. The trading suspensions will last for 10 business days. The trading suspensions commenced today at 9:30 a.m., EDT, and terminate at 11:59 p.m., EDT, on March 21.

The trading suspensions are part of a stepped-up SEC effort — code named “Operation Spamalot” — to protect investors from potentially fraudulent spam e-mail hyping small company stocks with phrases like, “Ready to Explode,” “Ride the Bull,” and “Fast Money.” It’s estimated that 100 million of these spam messages are sent every week, triggering dramatic spikes in share price and trading volume before the spamming stops and investors lose their money.

“When spam clogs our mailboxes, it’s annoying. When it rips off investors, it’s illegal and destructive,” said SEC chairman Christopher Cox. “Today’s trading suspensions, and actions that will follow, should send a clear message to spammers: the SEC will hold you accountable.”

Linda Chatman Thomsen, director of the SEC’s Enforcement Division, said, “Many of these companies are no doubt familiar to anyone who reads their email, because each has been the subject of a spam email campaign. While the commission cautions investors not to make investment decisions based on anonymous emails they receive, we are also committed to tracking down those who prey on investors with false or misleading information.”