Should “glitches” like these concern investors?  Should you be concerned if your retirement funds are in a market that has flash crashes, trading halts, and computers executing trades and trading strategies by the millisecond?

All good questions.  I don’t have a definitive answer.  Let me quote Robert Reich’s “Aftershock”: “Wall Street is a casino in which high stakes wagers are placed within a limited number of betting houses that keep a percentage of the wins for themselves and fob off losses on others, including taxpayers.”

If you have money in the market I suggest you buy low and sell high.  For example,  Netflix has  price to earnings ratio of 335 now.  The historical average for the market in general is roughly 15.  This seems like a sell high opportunity.  Yes, it could go higher.  But isn’t a P/E of 335 high enough?

http://mobile.nytimes.com/2013/08/23/business/daily-stock-market-activity.html