I might do it incorrectly but here's an example of the way I play the FV.
SP cash closed yesterday at 1160.7
The SP futures (which close 15 min. before the market opens) closed at 1166.5 this morning.
I use the FV from this site
http://www.programtrading.com/buysell.htm
This morning FV was 1.25
I add 1.25 and SP cash of 1160.7 = 1161.95.
Then I find the difference between futures and cash (with the FV number added to the cash) 1166.5-1161.95=4.55 (note that today it's a positive number.)
Then I find the percentage of change this difference is from the SP close- eg: 4.55/1160.7=.0039.
Okay, .0039 is my number.
I add/subtract that % from a given stock's previous close (today I add since it's positive, the overnight futures closed higher than cash/fv--the market will open "up".)
I'll use TXN as an example. It closed yesterday @ 29.00.
So, 29.00x.00392=.113 or about 11 cents.
I add .11 to 29.00 and, to me, TXN should open about 29.11 to be level with the world.
If TXN opens a distance from this number, plus or minus, that seems too far I'll take the trade. This is my envelope. Half a percent is common. Some traders will use more, others will use less.
So now, 29.11x.005=.145 or about 15 cents.
29.11-.15= 28.96 or less and I buy.
29.11+.15=29.26 or more and I short.
TXN opened @ 29.75. It was a short according to this method.
I use this method even though I trade retail. I sometimes get better fills than "opening only" orders because I can come in shortly after the open with discretion. I've noticed that some specialists like to put a little shake on the stock before it moves the right direction (I figure they're adding to their short/long but I dunno) TXN traded as high as .84 before dropping some.
Warning: this is my cobbled together version of some unclear info that I received and it may not be quite right. Use at your own risk.
If I'm off on this I'd really appreciate any help.
Mike