That's Wall Street High Frequency Trading.

I was just reading this article on HFT and thought that everybody should be aware of what's going on here.

Basically how it works, is that big traders on Wall St. are able to tap into large orders made by mutual funds, etc. and buy before the order has gone through. By the time the mutual funds buy the stock, the price has already risen and the Wall St. leeches make a profit.
Also, there are areas of the stock market where the general public never have access, the article writer calls them "dark pools".

If you're concerned at all about where your share portfolio or Super. fund is going, this article is well worth a peruse:

http://articles.moneycentral.msn.com/Investing/CompanyFocus/wall-sreets-high-tec...