At 2:42 pm on May 6, 2010, the Dow Jones Industrial Average (DJIA) suddenly plunged by about 1,000 points within about 20 minutes. It sliced $1 trillion in investor wealth. As a result, it became known as the "Flash Crash." While the cause is far from certain, it does look like there were some major trades that tripped-up algorithmic trading systems (these use sophisticated computers for high-frequency trading).

No doubt, the Flash Crash had a jarring impact on retail investors. Could the markets be trusted? Were they safe?

On May 6, we saw the Dow plunge almost 1,000 points in a matter of minutes. To date, no one has pinpointed the cause of the crash.

Meanwhile the Securities and Exchange Commission (SEC) has been scrambling to plug the leak in the dike. An article in USA Today outlines the expanded SEC rules.

With sophisticated high-frequency trading and quant funds, it seems that the proverbial Hal 9000 has taken over Wall Street. Of course, a stark example of this was in May 6, in which the market inexplicably lost $862 billion in market value within 20 minutes. It was the "Flash Crash."

Since then, the SEC and other government regulators have been investigating the matter. Already, there are some changes that have been put in place, such as circuit breakers. And yes, these have been triggered in some cases already.

New circuit breakers will take effect next week on the NYSE aimed at preventing another "flash crash." Under this new system, halts are triggered based on where the price of the stock was trading during the previous five minute period. They will be in effect from 9:45 a.m. to 3:35 p.m.

During the crash of May 6, some stocks crashed to near zero. For example, Accenture (ACN) plunged from $40 to an incredible penny per share.