Thanks for the insight.. of course I can trade after hours but as you said liquidty dries up and spreads widen.. it's not that I can't figure out how to close out the position, but it's not really what I'd like to spend my time on doing. I can always enter the trade at any point between stop-time(threshold determined by my model when to start winding down) and the market close, even after hours, but there is no obvious optimal point.. if GS's algos can split it up and gaurantee that it'll execute at least somewhat efficiently i'd just rather fire and forget near the end of the day. Basically, my model calculates the half-life of the time until my positions should be fully closed, and that estimate is continually updated with every tick, but as end of day approaches I have to balance the half life with the real cut off time. I guess there is some room for me to build it into my algos after all.