A paper or two was published on the anomaly and now more money is trading it. Still good if you can isolate the companies that are being bought into buy larger funds, but that requires a bit more work (13-f stuff, cross examining vs. mandate, seeing if company is actually performing well financially to be a good add, etc.) which means the returns are getting muddled. In other words, what started as an almost easy trade (list all stocks seeing higher volumes in last 30 min, buy 1 hour before) has become more efficient (need to find additional sources of edge/alpha for trade to work).What caused this trade lost its edge?
If you are trading sub-500k you can probably still do this on a curated list of names providing you calculate % chg in AVAT (average volume at time).