It's a bull market for stock spam

Though traditional spam categories--medication, mortgage and pornography--continue to dominate, new ones such as stock scams are growing, according to the study, which covered the first six months of 2005.

Medications, including unbranded versions of Viagra, accounted for 40 percent of all spam traffic, the study said. This was followed by mortgages at 11 percent and porn at 9.5 percent. Stock-related spam came in fourth place at 8.5 percent of the total spam traffic. The volume of "pump-and-dump" stock scam e-mail has increased at an average rate of 10 percent per month, the company said.

"The purpose behind the pump-and-dump stock racket is to quickly and cheaply disperse false information about a company's stock, along with information obtained from recent press releases, to potential investors via e-mail," Gregg Mastoras, senior security analyst at Sophos, said in a statement. "Typically targeting microcap companies' stock, once these fraudsters dump their shares, and then stop advertising the stock, the price often falls, and investors ultimately lose their cash."

Sophos said stock campaigns usually run for short periods. Though some of the information given is accurate, the deceptive and unsolicited nature of these e-mails qualifies them as spam. They generally use word variations such as "st0ck" or "stox" to avoid being stopped by spam filters.

Stock scams, combined with traditional phishing techniques, can result in significant financial loss for victims of these swindles, the security firm said, quoting IDC analysts.