No problem, yes, those round figures are quite popular even with retail investors (tuulipuvut). They are indeed not all bots, but one must remember that 80-90% is bot trading. However, you can recognize which ones are not quite normal, for example, trades of 277 pieces 
I myself believe that the level close to $5.50 is enough for the Americans, meaning that 50k $5.5 puts are almost worthless. At the same time, there’s a small number of $6 puts, and a large part of the value is lost from $5 calls. The idea is that $5 requires too much effort, although with Helsinki’s volume, even a retail investor (tuulipuku) can influence the price (which is, of course, forbidden 
). But in the US, we’re probably going over 25m shares today, I’d think there would be hedges open as well…
That picture is quite amusing, of course, there’s market segmentation involved, but certainly not exclusively.
