Having the scumbag of a CEO in the headline may have been a mistake. Riccitiello sold the least shares in the recent transaction history of the company. Also, I don’t know where you get your "retaining over 3000000 shares’ from. The source says Riccitiello sold all his shares in his possession.
The article mentions two others:
Tomer Bar-Zeev who sold 37.5k shares on 1st September, for around $1.4m. Shlomo Dovrat, meanwhile, sold 68k shares on 30th August for around $2.5m.
Bar-Zeev sold 37500 shares of ~1300000 owned on automated sell. That’s a factor of ten and a fair bit away from 2k sold from 3 mil, but that might be normal. It was automated, after all.
Dovrat’s transaction is mostly the same, roughly double the shares sold and roughly double the shares owned. However, it was not automated.
I believe the article mentioned them because they sold the most, but they clearly weren’t taking the amount retained into account. The third most sold, however, by Robynne Sisco was a sell of 25768, retaining 14700 (sold ~64%).
There are a fair number of other sells, but if the Bar-Zeev and Dovrat sells don’t look suspicious, nothing else will stand out.
What does seem a little odd- and I have no idea if this is at all unusual- is that in the last twelve months, more shares have been bought than sold (net shares almost 10,000,000), and in the last 3 months more shares have been sold than bought (net shares almost 3,500,000). In the last 3 months, the number of insider traders is a little over 1/3 of the amount of insider trades over the last 12 months (under the assumption it should be about 1/4). All of the insider buys seem to be the options granted for working for Unity. I assume it isn’t too odd for the board of directors to sell and never buy, but they have increased selling a fair bit in the last 3 months, and it seems specifically the last two weeks.