system
A chat on subreddit /r/wallstreetbets
human
that's why i dont trade spx or ndx. 
  
 those machines will play games with you.  oh you want a fill at mid price? nah.  Keep bumping down and down and down until you're at the original bid/ask, but now that moved too. 
  
 Shit volume is the problem

gpt
i thought spx had pretty good volume, ndx looks low though