pre-market and afterhours is a waste of time unless you like working 12 hours day. it seems like everybody turns off their computer trading programs all at once once clocks strikes 4:15 pm EST. and volume evaporates and only guy on the bid and ask is one market maker (computer) automated market makers with on order or 100 shares. with 1 penny to 10 penny spread.
Ya, and in this last 15min on the SPX you can see some weird things happening. You can see my P&L on a SPX condor go from +$250 durning the day to -100 in these last 15min to where they close the prices. It paints a bad P&L in your portfolio every night. lol I guess it is so when others are pricing condors and spreads at night, they see all these huge premiums that they can sell these condors for whenever they prices them at night, however, when they try to get these prices during the day, there is no way on earth that they will get a fill.
Don't forget that news - lots of earnings - are released during those 15 minutes and it's very reasonable for option quotes to change. Mark