COO Mark Miller doing something similar to what Mark Leonard did (but this one not over a year, just over a couple months, but with higher number of shares per month):
https://www.globenewswire.com/news-release/2019/03/13/1752885/0/en/COO-of-Constellation-Software-Enters-into-Automatic-Share-Purchase-and-Disposition-Plan.html
They really want to keep the price down. Which ironically is kind of a bullish signal, as you want management that focuses on talent retention and not the stock, and a stock that is high can be a problem for that. But at the same time, these guys (Leonard and Miller) are so financially conservative and probably have such high hurdles that what they consider fair value is probably lower than what most people would consider fair... We'll see how the market reacts and whether the gambit works or if the market sees things differently.
The timing to May 31st makes me wonder if this is because employee bonus open-market stock purchases are mostly during this time of the year...
Btw, the stock is going ex-dividend for the $20US special dividend today, so about $26CAD of the price move today is because of that.