I trade a mechanical system that takes profits at the end of day, it seems that 4:15 is better time to take profits as on a trending day the market keeps going in the direction of the days between 4:00 and 4:15. I dont have a any back data to test this though. My only concern might be news events that occur just after the close. Or are after market news events posted afer 4:15?
To tell you the truth, looking at 4 pm vs 4:15 pm... I have seen a 10 point difference at most within the past few days, just scrolling back on my chart. I guess it depends if you are on the right side of the trade or not.
Have not back tested but eod exit for an uptrend day I would think could be 4:12 but a downtrend day does't close at LOD as often as an uptrend day closes at HOD. This should also be in context of Are dailys in an uptrend or downtrend? A trend day which is against the dailys would reverse more often. All just my opinion.
I can only add empirical data (my own eyesight). The moves in the fifteen minutes between the NYSE close and the CME close are random and yes often quite volatile. I manage to lose money in that time period either way. On trend days that I'm with there's often sharp reversals or when I'm a late fader there's continuation after stocks are closed.
i usually flatten all my position trades by 16:00 EST --- only trades that i know i am going to hold overnight do i keep on past this time period. just makes it much easier and it has worked well for me over the years. today by 15:00 EST i decided to just hold some of my es position trade shorts through until tomorrow as the market was toast ---- so i did not care what the last 15 minutes did and i wanted to get back to my air combat video game. i was flying a P-51 against german ME-163's with a microsoft air combat simulator i have set up in my office. those little buggers are hard to dogfight ---------------------------------------------- http://www.xs4all.nl/~robdebie/me163.htm great way to call it a day and have some fun!