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A new study reveals that spam messages promoting stocks can make you money – if you’re the spammer.

“Hot Energy! Oil Stock!” shouts the typical message. “Ready To Run!! Big Winner!!! Huge Advertising Campaign This Week!” Such come-on messages often refer to a company with a listing on the Pink Sheets, an over-the-counter stock quotation system. They’re designed to entice novice traders to buy stocks that are normally overlooked.

These annoying campaigns are growing in frequency and volume. Sophos, a Massachusetts-based supplier of software for protecting companies and consumers from online threats, reported in July that 15 percent of all junk e-mail messages are now stock spam, up dramatically from less than 1 percent 18 months ago.

So why is stock spam on the rise – and adapting quickly to technologies designed to stomp it out?

“It’s not that it’s just cheap to send, but it actually gets results,” says Jonathan Zittrain, professor of Internet governance and regulation at Oxford University, and co-author of a new study, “Spam Works: Evidence from Stock Touts and Corresponding Market Activity.” He’s also co-founder of the Berkman Center for Internet & Society at Harvard Law School.

Stock spam uses the classic “pump-and-dump” scheme. A spammer sends out a mass e-mail message touting a penny stock with low trading volume in hopes of convincing a handful of people to buy shares of it. If the spammer succeeds, the limited buying activity boosts the stock’s price and liquidity just long enough for the spammer to sell his own shares (or the shares of his client) at a profit. The stock subsequently plunges and those who bought it are usually hit with a loss.

In their study, Zittrain and co-author Laura Frieder, an assistant professor of finance at Purdue University in Indiana, sought to quantify the effectiveness of such campaigns. To do so, they analyzed more than 75,000 stock “touts” appearing in Zittrain’s e-mail inbox and a Usenet spam-sighting newsgroup between January 2004 and July 2005. The date and estimated size of each spam campaign was compared with the price and trading volume of the company shares being promoted over several days, including the day immediately preceding the campaign.

The researchers discovered that if a spammer bought a stock a day before beginning heavy touting, then sold the morning after the first day of touting, the average return on investment was 4.9 percent. And more effective spammers saw a 6 percent return.

On the other hand, if a victim were to invest $1,000 in a stock on the day of heaviest touting, that investment would be worth, on average, $947.50 in the two days following the spamming campaign. For the most heavily touted stocks, the same investment would fall by 7 percent, to $930. The study also confirmed that the volume of touted stocks responded “positively and significantly” to touting campaigns, meaning that trading activity increased.

“Our analysis shows that [stock] spam works,” wrote Zittrain and Frieder. “Among its millions of recipients are not only those who read it, but who also act upon it, suggesting a value to spamming that will create a powerful counterbalance to regulatory and technical efforts to contain it.”

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