the seemingly irrationally low number of shares traded, often seen on L2. Maybe this explanation I stumbled upon explains it. Sorry for the presentation. I didn't know how to resolve it. :>)

" 1) Retail traders account for a small proportion of total volume;

2) Large traders are heavily using order execution software to break their large orders into small pieces.

I performed a very simple exercise and examined the first hour of trading in a popular stock, AAPL. There were almost 57,000 trades in the first hour alone.

By my calculation of how the trades were reported, roughly two-thirds of these trades were broken down into small pieces for execution. Over three-quarters of all first-hour trades were 100 shares. Of the small, 100-share trades, I estimate that about two-thirds were part of larger trades that were executed in pieces by specialized software."S

In other words, if you were to simply look at trades and trade volume, you'd conclude that small traders were dominating the marketplace. The reality is, however, that large traders continue to hold sway, but have succeeded in disguising their presence.