Many company boards (of which CEOs sit at) have requirements where they must vest a minimum dollar amount into acquiring company shares. The purpose of this is to ensure they have an interest in the success of the stock and thereby the success of the company.
These same companies will then additionally have blackout periods typically 30 days before the announcement of quarterly earnings where employees are restricted from selling shares.
Not sure what unity's board rules are but if they are a public company it should be in their investors materials, annual reports, etc
All execs sell their own stock all the time. You're just aware of it today for one company so it seems like an issue.
Riccitiello has 3 million shares. He sold 2k (.06%) recently and 50k (1.5%) YTD.
You should also be made aware that when you are identified as a director of a company, trades like this are generally automatically scheduled due to MNPI regulations.
https://www.gurufocus.com/stock/U/insider
Tim Apple sells about a million shares of AAPL every year, while holding roughly 3M continuously. Likely all pre-planned on a schedule.
https://www.gurufocus.com/stock/AAPL/insider