That question has been answered many many times over the years in Don's thread.Quote from reid5525:
What is the concept for opening orders trading. I must ask because at the open you do not have any idea which way the stock will go.
What's your rational for trading stocks with potential for small intraday trading ranges.
I am not going to rehash it again, but the basic idea is that there is a relation between where a stock that is affected by the SP futures should open in the absence of any news or other external forces and where it actually opens due to a buying or selling imbalance that builds up overnight.
You then add and subtract conservative padding to that "fair value" to get where you go short and where you would go long on the opening print. If the opening print is anywhere at or outside of those two Opening Limit Orders, you get that price improvement and participate on the opening print. The hope is that the imbalance was temporary and the stock mean reverts enough for you to take a profit.
Otherwise if the Opening print is inside your two Limit Orders, the orders automatically cancel.
Put out that net for enough stocks and combine it with trading skill and VERY LOW commissions and ACCESS TO LOTS OF CAPITAL and you have yourself an edge.
nitro