Employee shares usually get put in a 3-6 month lockdown so they don't get to participate in the bubbly robinhood excitement.

It's also often also part of the employee retention plan. If you discover your boss has lied to you shortly after an IPO or a merger, then odds are good they were trying to hold onto you by any means necessary until their bonus was paid out.

I've had several people I trusted destroy our relationship this way over the years.

The s1 lays out the exact schedule and let me tell you it is not a normal schedule. Is that a surprise anymore though?

Oh wow, I looked it up. Employee's get to sell up to 10% on day 1. That's cool for them.