goombah99 writes "The SEC has taken action to halt transactions on spam-touted stocks. Presumably this opens an opportunity for denial of service attacks on stocks. However, to be effective spam generally must target penny stocks with historically low volumes and thus the actual capitalized market impact or effect on the companies for a temporary shutdown can be expected to be negligible and transient. One example was given of a touted apparel stock jumping from 6 cents to 45 cents over a period of days before settling down to ten cents a share and near 65,000 or about $6500 in transactions (an eighth of the peak share volume, and a 50th of the peak transaction value). In other words, the market distortion of a brief shutdown, even if it were a DOS attack, would be massively less than the integrated spam surge. The thing I found surprising was that for this to be an effective measure with human oversight then the number of such events must be relatively small in number. From the amount of spam I get I'd have guessed it was a tidal wave."