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