let me add to this since the link is included in the article:
https://seekingalpha.com/article/414...s-warning-svxy
before i bought a flip, late 2 years ago/very early last year, most of my grist cash on a day to day was tied up in this. if I had money allocated, I refused to leave my desk for more than an hour and always had to have my phone. an exploitable pattern emerged from people like me who would always close out end of day, every day. eventually closing out (for me) would be around 2pm and by that point margins after transactions was becoming nil and the only profitable days would have been like during the NK 'crisis' (although I had closed out by then), albeit there were easy 10% gains each day of trading those days if you bet with then against prevailing opinion quick enough.
weird seeing it finally blow up overnight.