No, this is not insider trading. Unethical yes, but not illegal. Sokol bought shares in January for his personal account because he liked the company and its business model. The guy’s rich - him throwing $10 million at a company he likes is nothing.
After looking more closely at the company, he realized it’s a real good business model and would be a good acquisition for BH. Stuff like this happens all the time at all levels of investing when you work on the buyside, and there’s nothing illegal about it.
At this scale (tho’ (when your company is going to acquire a company you recently bought personally) the ethical thing to do would be to divest the personal shares before the acquisition announcement.
Sokol didn’t do that, so bye-bye.