There are a number of issues at play here, but short answer, you are not legally obligated to work at all, you can leave any time.
With that said the issues involved are as such:
1. If you had equity in a company (and sometimes even if you don't) it is not uncommon to sign a non-compete contract as part of the sale that bars you from working for a competitor for about a year.
2. Often, much of the value of the sale for employees is structured as retention payments, i.e. they set up a number of bonuses that are spread out over a few years, and you need to work at the company for that duration to get those bonuses.
With that said the issues involved are as such:
1. If you had equity in a company (and sometimes even if you don't) it is not uncommon to sign a non-compete contract as part of the sale that bars you from working for a competitor for about a year. 2. Often, much of the value of the sale for employees is structured as retention payments, i.e. they set up a number of bonuses that are spread out over a few years, and you need to work at the company for that duration to get those bonuses.