What is likely to have happened here? Did an institutional investor get wind of the story early? If so, why did the share price jump up?
Typically, if you're in a position where you'll often have material non-public info you need to create a trading plan in advance, or otherwise remove your ability to trade the company based on all the secret stuff you're always going to be knowing. Look at it that way and for the CTO of a large public co., their own departure is just going to be the last of many, many pieces of info make it problematic for them to trade the stock.