The most frequently-asked question about stock spam is "How can I get stock spammers to stop spamming me?" The next most frequently-asked questions seem to be "Does stock spam work?", and "Can I do something to profit from stock spam?". Some recent studies appear to hint at an answer to the second and third questions.
A number of studies have suggested that stock spam does boost stock prices. This has probably led some investors to believe that if they buy stocks immediately on receiving spam, they can profit from the rise in price.
This news made me slightly uneasy. If the price of a stock rises because naive investors buy in, the major beneficiary is going to be the spammer. I don't like the idea that investors might use the spammed stocks list on this site to decide what to buy, resulting in a bigger payoff for the spammer. (Incidentally, you'd be foolish to do this because the list is not updated in real time: there can be significant delays before certain spams are registered). The purpose of this site is definitely not to help spammers fleece clueless buyers.
Recent studies suggest that this would be a bad strategy in any case. Anyone who tries to ride on the spammer's coat tails by buying a stock as soon as the first spams are seen is likely to lose money. On average, an investor who purchased a stock on the day that it was most heavily advertised would lose 5-7% of the value of their investment on the two days following the campaign.
The spammer, on the other hand, stands to make a modest profit. The study by Laura Frieder and Jonathan Zittrain indicates that buying the day before a spam campaign starts and selling the day after will yield a return of about 5%. Naturally, the spammer's profits come at the expense of other investors, who will see the value of their own investments decline.
The spammer's big advantage is that they have inside knowledge. They know which stocks they are going to buy, they know how long the spam campaign will last, and they can predict approximately how the stock is likely to behave. An investor who buys into the spammed stock is in a very different position. They can never know whether the first spams they see are the beginning or the end of a campaign, whether the stock has passed its peak or is just starting to rise. The spammer knows when to buy and sell. The investor doesn't, making it more likely that they'll end up with a loss than a gain.
Some people have wondered whether it would be worth shorting a spamvertized stock. To short a stock is essentially to bet that the stock will lose value. If spamvertized stocks can be counted on to lose value in the days following a spam campaign, shorting the stock when the first spams are seen might offer investors the opportunity to pick up some profits after all.
Personally, I wouldn't recommend this. Short selling is commonly viewed as a risky strategy. If you buy a stock expecting its value to increase, your potential loss is limited - the most you can lose is the entire value of your holding - but your potential gain is unlimited. When you short a stock, the reverse is true: you're risking a theoretically unlimited loss in the hope of a limited gain.
Stock traders can make money shorting stocks, but they generally do so when they have good information about the way that the stock will behave. Unfortunately, just knowing that a stock has been spamvertized doesn't really tell you much about what the stock will do in the near-term. When you see a spam for a particular stock, you have no way of knowing how long the spam campaign - and the consequent artificial price rise - will continue. You have no way to be certain that a second spammer, seeing an easily manipulable stock that has already gathered some share of attention, won't decide to jump in and start a spam campaign of their own (I've seen some evidence to suggest that the same stocks are indeed being manipulated by more than one spammer). To short a spammed stock is to make a risky bet in the belief that you know more than you actually do about how the stock will behave, and that's a good recipe for losing money.
The conclusion is simple and not unexpected: the best thing that you can do with spamvertized stocks is to leave them strictly alone.